Stockholders' Equity and Noncontrolling Interests (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Class of Stock [Line Items]
Income attributable to noncontrolling interests	$ 2,911	$ 2,620	$ 6,581	$ 6,046
Depositary shares outstanding (in shares)	7.2		7.2
6.875 Series C Cumulative Redeemable Preferred Stock
Class of Stock [Line Items]
Depository shares to cumulative redeemable preferred stock ratio			1.00%
Percentage of redeemable preferred stock			6.875%
Cumulative redeemable preferred stock liquidation preference (in usd per share)	$ 25.00		$ 25.00
Annual dividend on depositary shares (in usd per share)			$ 1.71875