Discontinued Operations and Disposition of Real Estate and Real Estate Investments - Operating Results Related to Assets Sold (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Discontinued Operations And Disposal Groups [Abstract]
Revenues	$ 39,537	$ 81,241	$ 102,552
Expenses
Operating expenses	11,070	23,204	29,103
Impairment charges	8,877	53,553	79,731
Interest, net	9,947	19,457	25,745
Depreciation and amortization	16,254	27,568	31,184
Total expenses, discontinued operations	46,148	123,782	165,763
Loss from discontinued operations	(6,611)	(42,541)	(63,211)
Gain on disposition of real estate, net of tax	96,009	11,274	3,847
Income (loss) from discontinued operations	$ 89,398	$ (31,267)	$ (59,364)