Real Estate Leases

The Company’s properties are generally leased pursuant to non-cancelable, fixed-term operating leases with expiration dates through 2036. Some leases and financial arrangements provide for fixed rent renewal terms in addition to market rent renewal terms. Some leases provide the lessee, during the term of the lease and for a short period thereafter, with an option or a right of first refusal to purchase the leased property. The Company’s portfolio of single-tenant net leases generally requires the lessee to pay minimum rent and all taxes (including property tax), insurance, maintenance and other operating costs associated with the leased property.

Future minimum lease payments under the non-cancelable operating leases and guaranteed amounts payable to the Company under property operating agreements as of December 31, 2017 are as follows (in thousands):



2018	$	330,526
2019	282,910
2020	236,454
2021	196,346
2022	168,183
2023 and thereafter	544,677
	$	1,759,096

Revenue Concentrations

The Company’s real estate portfolio is leased to a diverse tenant base. The Company's largest revenue concentration is with Baylor Scott & White Health and its affiliates which accounted for 9.7%, 9.8% and 9.8% of the Company's consolidated revenues for the years ended December 31, 2017, 2016 and 2015, respectively.

Purchase Option Provisions

Certain of the Company’s leases include purchase option provisions. The provisions vary by agreement but generally allow the lessee to purchase the property covered by the agreement at fair market value or an amount equal to the Company’s gross investment. The Company expects that the purchase price from its purchase options will be greater than its net investment in the properties at the time of potential exercise by the lessee. The Company had approximately $95.2 million in four real estate properties as of December 31, 2017 that were subject to purchase options that were exercisable.