12.

Leases

We maintain operating lease agreements principally for our office spaces. We lease approximately 264,000 square feet of office space for our corporate headquarters in Franklin, Tennessee, approximately 221,000 square feet of which is subleased. This lease commenced in March 2008 and expires in February 2023. We also lease approximately 92,000 square feet of office space in Chandler, Arizona, and approximately 13,000 square feet of office space in Sterling, Virginia. The Chandler, Arizona lease began in April 2009 and expires in April 2020.

Our corporate office lease agreement in Tennessee contains escalation clauses and provides for two renewal options of five years each at then prevailing market rates. The base rent for the initial 15-year term ranges from $4.3 million to $6.6 million per year over the term of the lease. The landlord provided a tenant improvement allowance equal to approximately $10.7 million. We record leasehold improvement incentives as deferred rent and amortize them as reductions to rent expense over the lease term.

Most of our operating leases include escalation clauses, some of which are fixed amounts, and some of which reflect changes in price indices. We recognize rent expense on a straight-line basis over the lease term. Certain operating leases contain renewal options to extend the lease for additional periods. For the years ended December 31, 2016, 2015, and 2014, rent expense under lease agreements was approximately $4.2 million, $3.7 million, and $2.0 million, respectively. Our capital lease obligations are included in long-term debt and the current portion of long-term debt.

The following table summarizes our future minimum lease payments, net of total cash receipts from subleases of $33.9 million, under all capital leases and non-cancelable operating leases for each of the next five years and thereafter:

(In thousands)	Capital		Operating
Year ending December 31,	Leases		Leases
2017	$	95	$	5,699
2018		56		5,336
2019		—		5,427
2020		—		2,999
2021		—		859
2022 and thereafter		—		963
Total minimum lease payments	$	151	$	21,283
Less amount representing interest		—
Present value of minimum lease payments		151
Less current portion		95
	$	56