Stockholders' Equity and Noncontrolling Interest - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended			12 Months Ended
	Nov. 12, 2014	Feb. 12, 2013	Mar. 31, 2013	Mar. 31, 2008	Nov. 30, 2003	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Class of Stock [Line Items]
Income attributable to noncontrolling interests						$ 10,463	$ 11,045	$ 3,970
Series A Preferred Stock
Class of Stock [Line Items]
Number of depositary shares sold					4,000,000
Dividend rate on preferred stock					8.00%
Depositary shares, redeemable price (in usd per share)					$ 25.00
Annual dividend on depositary shares					2.00
Cumulative redeemable preferred stock liquidation preference					$ 25.00
Percentage of redeemable preferred stock			60.00%
Depository shares to cumulative redeemable preferred stock ratio					1.00%
Series B Preferred Stock
Class of Stock [Line Items]
Number of depositary shares sold				3,173,115
Dividend rate on preferred stock				9.00%
Depositary shares, redeemable price (in usd per share)				$ 25.00
Annual dividend on depositary shares				2.25
Cumulative redeemable preferred stock liquidation preference				$ 25.00
Depository shares to cumulative redeemable preferred stock ratio				1.00%
Series C Preferred Stock
Class of Stock [Line Items]
Number of depositary shares sold	1,600,000	5,600,000
Dividend rate on preferred stock		6.875%
Annual dividend on depositary shares		$ 1.71875
Cumulative redeemable preferred stock liquidation preference		$ 25.00
Percentage of redeemable preferred stock		6.875%
Depository shares to cumulative redeemable preferred stock ratio		1.00%
Series C preferred stock	$ 39,260	$ 135,200				$ 0	$ 39,260	$ 135,221