Schedule III (Consolidated) - Real Estate and Accumulated Depreciation - Reconciliation of Real Estate Owned (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
SEC Schedule III, Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]
Balance at beginning of the year	$ 377,668	$ 379,944	$ 436,264
Amounts capitalized	13,875	13,372	26,047
Impairments	(357)	0	0
Cost of real estate sold	(6,489)	(14,584)	(76,060)
Amounts retired or adjusted	(2,728)	(1,064)	(6,307)
Balance at the end of the year	$ 381,969	$ 377,668	$ 379,944