Schedule III - Reconciliation of Real Estate and Accumulated Depreciation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
SEC Schedule III, Real Estate and Accumulated Depreciation Disclosure [Abstract]
Beginning balance	$ 607,133	$ 547,530	$ 545,370
Amounts capitalized	124,633	214,184	111,428
Amounts retired or adjusted	(112,922)	(154,581)	(109,268)
Ending balance	618,844	607,133	547,530
Beginning balance	(31,377)	(28,066)	(28,220)
Depreciation expense	(6,810)	(3,319)	(2,185)
Amounts retired or adjusted	6,058	8	2,339
Ending balance	$ (32,129)	$ (31,377)	$ (28,066)