Schedule III - Changes in Accumulated Depreciation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017		Dec. 31, 2016	Dec. 31, 2015
SEC Schedule III, Real Estate and Accumulated Depreciation Disclosure [Abstract]
Balance at beginning of period	$ 292,786		$ 232,675	$ 181,441
Depreciation	109,307		81,010	60,796
Depreciation on disposed property	(1,438)		(19,086)	(8,887)
Other	6,694		(1,813)	(675)
Balance at end of period	$ 406,855	[1]	$ 292,786	$ 232,675

[1] Includes accumulated depreciation in real estate held for sale of $0.5 million. Excludes accumulated amortization related to intangible lease assets that are included in real estate held for sale of $0.1 million for 2017.