Income Taxes - Deferred Income Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Gross deferred income tax assets:
NOL carryforwards	$ 334,358	$ 350,909
Basis difference – real estate properties	53,902	56,827
Basis difference – equity investments and intangibles	4,740	4,666
Section 163(j) interest limitation	26,280	40,766
Capital loss carryforward	10,566	25,145
Other – temporary differences	5,724	5,578
Total gross deferred income tax assets	435,570	483,891
Valuation allowance	(410,896)	(456,699)
Gross deferred income tax assets, net of valuation allowance	24,674	27,192
Gross deferred income tax liabilities:
Basis difference – real estate properties	63,246	70,914
Basis difference – equity investments and intangibles	1,114	6,864
Other – temporary differences	769	1,028
Total gross deferred income tax liabilities	65,129	78,806
Net deferred income tax liabilities	$ 40,455	$ 51,614