Consolidated Statements of Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total USD ($)	Class A	Class B	Common Stock USD ($)	Common Stock Class A	Common Stock Class B	Additional Paid-In Capital USD ($)	Cumulative Dividends in Excess of Earnings USD ($)	Total Stockholders’ Equity USD ($)	Noncontrolling Interest USD ($)
Beginning balance at Dec. 31, 2010	$ 1,487,246			$ 2,026			$ 1,795,413	$ (310,193)	$ 1,487,246	$ 0
Beginning balance, shares at Dec. 31, 2010				202,644,000	0	0
Increase (Decrease) in Stockholders' Equity
Issuance of common stock (in shares)				21,682,000	0	0
Issuance of common stock	214,641			216			214,425	0	214,641	0
Offering costs	(18,896)			0			(18,896)	0	(18,896)	0
Share-based award transactions, net (in shares)				62,000	0	0
Share-based award transactions, net	3,221			1			3,220	0	3,221	0
Issuance of common stock under the DRIP (in shares)				7,986,000	0	0
Issuance of common stock under the DRIP	75,864			80			75,784	0	75,864	0
Repurchase and cancellation of common stock (in shares)				(3,883,000)	0	0
Repurchase and cancellation of common stock	(37,680)			(39)			(37,641)	0	(37,680)	0
Dividends	(162,597)			0			0	(162,597)	(162,597)	0
Net income (loss)	5,541			0			0	5,541	5,541	0
Ending balance at Dec. 31, 2011	1,567,340			2,284			2,032,305	(467,249)	1,567,340	0
Ending balance, shares at Dec. 31, 2011				228,491,000	0	0
Increase (Decrease) in Stockholders' Equity
Share-based award transactions, net (in shares)				626,000	333,000	12,000
Share-based award transactions, net	17,408			10			6,954	0	6,964	10,444
Issuance of common stock under the DRIP (in shares)				3,362,000	0	0
Issuance of common stock under the DRIP	31,916			34			31,882	0	31,916	0
Repurchase and cancellation of common stock (in shares)				(3,070,000)	(14,958,000)	(144,000)
Repurchase and cancellation of common stock	(185,486)			(181)			(185,305)	0	(185,486)	0
Conversion (in shares)				(229,409,000)	114,711,000	114,698,000
Dividends	(142,159)			0			0	(142,044)	(142,044)	(115)
Net income (loss)	(24,424)			0			0	(24,424)	(24,424)	0
Ending balance at Dec. 31, 2012	1,264,595			2,147			1,885,836	(633,717)	1,254,266	10,329
Ending balance, shares at Dec. 31, 2012		100,086,387	114,566,254	0	100,086,000	114,566,000
Increase (Decrease) in Stockholders' Equity
Issuance of common stock (in shares)				0	21,873,000	0
Issuance of common stock	239,334			219			239,115	0	239,334	0
Share-based award transactions, net (in shares)				0	422,000	(15,000)
Share-based award transactions, net	5,724			4			2,467	76	2,547	3,177
Issuance of common stock under the DRIP	0
Repurchase and cancellation of common stock (in shares)				0	(52,000)	0
Repurchase and cancellation of common stock	(522)			(1)			(521)	0	(522)	0
Conversion (in shares)				0	114,551,000	(114,551,000)
Dividends	(133,984)			0			0	(132,680)	(132,680)	(1,304)
Net income (loss)	24,602			0			0	24,261	24,261	341
Ending balance at Dec. 31, 2013	$ 1,399,749			$ 2,369			$ 2,126,897	$ (742,060)	$ 1,387,206	$ 12,543
Ending balance, shares at Dec. 31, 2013		236,880,614	0	0	236,880,000	0