Reconciliation of Income Tax Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Tax benefit computed at federal statutory rate	$ 11,002	$ 23,701	$ 18,253
Impact of REIT election	(11,002)	(23,701)	(18,253)
State income tax expense	(351)	(378)	(361)
Income tax expense	$ (351)	$ (378)	$ (361)
Tax benefit computed at federal statutory rate	35.00%	35.00%	35.00%
Impact of REIT election	(35.00%)	(35.00%)	(35.00%)
State income tax expense	(1.12%)	(0.56%)	(0.69%)
Income tax expense	(1.12%)	(0.56%)	(0.69%)