Commitments and Contingencies Commitments Leases We have entered into various non-cancelable operating lease agreements for certain of our offices, data centers, land, and colocations with original lease periods expiring between 2019 and 2093 . We are committed to pay a portion of the related actual operating expenses under certain of these lease agreements. Certain of these arrangements have free rent periods or escalating rent payment provisions, and we recognize rent expense under such arrangements on a straight-line basis. The following is a schedule, by years, of the future minimum lease payments required under non-cancelable operating leases as of December 31, 2018 (in millions): Operating Leases 2019 $ 698 2020 946 2021 1,055 2022 1,048 2023 1,054 Thereafter 9,850 Total minimum lease payments $ 14,651 Operating lease expense was $629 million , $363 million , and $269 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. We fully repaid all our capital lease obligations during 2016. Guarantee In 2018, we established a multi-currency notional cash pool for certain of our entities with a third-party bank provider. Actual cash balances are not physically converted and are not commingled between participating legal entities. As part of the notional cash pool agreement, the bank extends overdraft credit to our participating entities as needed, provided that the overall notionally pooled balance of all accounts in the pool at the end of each day is at least zero. In the unlikely event of a default by our collective entities participating in the pool, any overdraft balances incurred would be guaranteed by Facebook, Inc. Other contractual commitments We also have $6.17 billion of non-cancelable contractual commitments as of December 31, 2018 , primarily related to network infrastructure and our data center operations. These commitments are primarily due within five years . Contingencies Legal Matters Beginning on March 20, 2018, multiple putative class actions and derivative actions were filed in state and federal courts in the United States and elsewhere against us and certain of our directors and officers alleging violations of securities laws, breach of fiduciary duties, and other causes of action in connection with our platform and user data practices as well as the misuse of certain data by a developer that shared such data with third parties in violation of our terms and policies, and seeking unspecified damages and injunctive relief. Beginning on July 27, 2018, two putative class actions were filed in federal court in the United States against us and certain of our directors and officers alleging violations of securities laws in connection with the disclosure of our earnings results for the second quarter of 2018, and seeking unspecified damages. These two actions subsequently were transferred and consolidated in the U.S. District Court for the Northern District of California with the putative securities class action described above relating to our platform and user data practices. We believe these lawsuits are without merit, and we are vigorously defending them. In addition, our platform and user data practices, as well as the events surrounding the misuse of certain data by a developer, became the subject of U.S. Federal Trade Commission, Securities and Exchange Commission, state attorneys general, and other government inquiries in the United States, Europe, and other jurisdictions. Beginning on September 28, 2018, multiple putative class actions were filed in state and federal courts in the United States and elsewhere against us alleging violations of consumer protection laws and other causes of action in connection with a third-party cyber-attack that exploited a vulnerability in Facebooks code to steal user access tokens and access certain profile information from user accounts on Facebook, and seeking unspecified damages and injunctive relief. We believe these lawsuits are without merit, and we are vigorously defending them. In addition, the events surrounding this cyber-attack became the subject of Irish Data Protection Commission, U.S. Federal Trade Commission and other government inquiries in the United States, Europe, and other jurisdictions. In addition, from time to time, we are subject to litigation and other proceedings involving law enforcement and other regulatory agencies, including in particular in Brazil and Europe, in order to ascertain the precise scope of our legal obligations to comply with the requests of those agencies, including our obligation to disclose user information in particular circumstances. A number of such instances have resulted in the assessment of fines and penalties against us. We believe we have multiple legal grounds to satisfy these requests or prevail against associated fines and penalties, and we intend to vigorously defend such fines and penalties. Although we believe that it is reasonably possible that we may incur a substantial loss in some of the cases, actions, or inquiries described above, we are currently unable to estimate the amount of such losses or a range of possible losses. We are also party to various other legal proceedings, claims, and regulatory, tax or government inquiries and investigations that arise in the ordinary course of business. With respect to these matters, we evaluate the developments on a regular basis and accrue a liability when we believe a loss is probable and the amount can be reasonably estimated. We believe that the amount or any estimable range of reasonably possible or probable loss will not, either individually or in the aggregate, have a material adverse effect on our business and consolidated financial statements. However, the outcome of these matters is inherently uncertain. Therefore, if one or more of these matters were resolved against us for amounts in excess of management's expectations, our results of operations and financial condition, including in a particular reporting period in which any such outcome becomes probable and estimable, could be materially adversely affected. For information regarding income tax contingencies, see Note 12Income Taxes. Indemnifications In the normal course of business, to facilitate transactions of services and products, we have agreed to indemnify certain parties with respect to certain matters. We have agreed to hold certain parties harmless against losses arising from a breach of representations or covenants, or out of intellectual property infringement or other claims made by third parties. These agreements may limit the time within which an indemnification claim can be made and the amount of the claim. In addition, we have entered into indemnification agreements with our officers, directors, and certain employees, and our certificate of incorporation and bylaws contain similar indemnification obligations. It is not possible to determine the maximum potential amount under these indemnification agreements due to the limited history of prior indemnification claims and the unique facts and circumstances involved in each particular agreement. Historically, payments made by us under these agreements have not had a material impact on our consolidated financial statements. In our opinion, as of December 31, 2018 , there was not at least a reasonable possibility we had incurred a material loss with respect to indemnification of such parties. We have not recorded any liability for costs related to indemnification through December 31, 2018 .