Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies.

Schedule of ground lease expense and office lease expense

	For the Year Ended
	December 31,
	2017		2016		2015
Ground lease expense	$	40,864	$	38,764	$	38,851
Office lease expense		4,481		4,105		4,067

Schedule of future minimum lease payments due under leases, excluding applicable extension options and any sublease income

Future minimum lease payments due under these leases for years ending December 31, excluding applicable extension options and any sublease income, are as follows:

2018	$	26,401
2019		25,936
2020		24,829
2021		24,061
2022		23,886
Thereafter		655,309
	$	780,422