Commitments and Contingencies: Leases We lease certain real and personal property under non-cancelable operating leases. Some of our lease agreements contain rent escalation clauses (including index-based escalations), rent holidays, capital improvement funding or other lease concessions. We recognize our minimum rental expense on a straight-line basis. We amortize this expense over the term of the lease beginning with the date of initial possession, which is the date we enter the leased space and begin to make improvements in preparation for its intended use. Future annual minimum lease payments and capital lease commitments as of December 31, 2017 were as follows (in millions): Operating Leases Capital Leases 2018 $ 55.3 $ 3.5 2019 42.4 0.6 2020 28.4 0.4 2021 18.3 0.1 2022 17.7  Thereafter 13.8 12.0 Total minimum lease payments $ 175.9 $ 16.6 Less amount representing interest 0.2 Present value of minimum payments $ 16.4 On March 22, 2013, we entered into an agreement with a financial institution to renew the lease of our corporate headquarters in Richardson, Texas for a term of approximately six years through March 1, 2019 (the Lake Park Renewal). The leased property consists of an office building of approximately 192,000 square feet, land and related improvements. During the lease term, the Lake Park Renewal requires us to pay base rent in quarterly installments, payable in arrears. At the end of the lease term, we must do one of the following: (i) purchase the property for $41.2 million ; (ii) vacate the property and return it in good condition; (iii) arrange for the sale of the leased property to a third party; or (iv) renew the lease under mutually agreeable terms. If we elect to sell the property to a third party and the sales proceeds are less than the lease balance, we must pay any such deficit to the financial institution. Any such deficit payment cannot exceed 86% of the lease balance. The Lake Park Renewal is classified as an operating lease and its future annual minimum lease payments are included