12. COMMITMENTS AND CERTAIN CONTINGENCIES Lease Commitments We lease certain facilities, furniture and equipment under operating leases. As of May 31, 2017, future minimum annual operating lease payments and future minimum payments to be received from non-cancelable subleases were as follows: (in millions) Fiscal 2018 $ 389 Fiscal 2019 330 Fiscal 2020 260 Fiscal 2021 203 Fiscal 2022 146 Thereafter 393 Future minimum operating lease payments 1,721 Less: minimum payments to be received from non-cancelable subleases (41 ) Total future minimum operating lease payments, net $ 1,680 Lease commitments included future minimum rent payments for facilities that we have vacated pursuant to our restructuring and merger integration activities, as discussed in Note 9. We have approximately $53 million in facility obligations, net of estimated sublease income and other costs, in accrued restructuring for these locations in our consolidated balance sheet at May 31, 2017. Rent expense was $273 million, $283 million and $290 million for fiscal 2017, 2016 and 2015, respectively, net of sublease income of approximately $87 million for fiscal 2017 and $45 million for each of fiscal 2016 and 2015, respectively. Certain lease agreements contain renewal options providing for extensions of the lease terms. Unconditional Obligations In the ordinary course of business, we enter into certain unconditional purchase obligations with our suppliers, which are agreements that are enforceable and legally binding and specify terms, including: fixed or minimum quantities to be purchased; fixed, minimum or variable price provisions; and the approximate timing of the payment. We utilize several external manufacturers to manufacture sub-assemblies for our hardware products and to perform final assembly and testing of finished hardware products. We also obtain individual components for our hardware products from a variety of individual suppliers based on projected demand information. Such purchase commitments are based on our forecasted component and m