Consolidated Statements of Changes in Equity (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	Total USD ($)	Common Stock USD ($)	Additional Paid-in Capital USD ($)	Accumulated Distributions in excess of Net Loss USD ($)	Accumulated Other Comprehensive Income (Loss) USD ($)	Noncontrolling Interests USD ($)	Tender Offer Event, Shares [Member]	Tender Offer Event, Additional Paid-In Capital [Member] USD ($)	Tender Offer Event, Common Stock [Member] USD ($)
Balance, value at Dec. 31, 2012	$ 4,342,750	$ 889	$ 7,921,913	$ (3,664,591)	$ 84,414	$ 125
Balance, shares at Dec. 31, 2012		889,424,572
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income Loss Attributable To Company Inclusive Of Noncontrolling Interest Excluding Noncontrolling Redeemable Interests				209,265		16
Net income	209,281
Unrealized gain on investment securities	13,993				13,993
Unrealized (gain) loss on derivatives	(53)				(53)
Reclassification adjustment from AOCI on derivatives and securities	(31,251)				(31,251)
Distributions declared	(336,665)			(336,649)
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders						(16)
Proceeds from distribution reinvestment plan, value	136,621	20	136,601
Proceeds from distribution reinvestment plan, shares		19,705,741
Share repurchase program, shares		(4,041,042)
Stock Repurchased During Period, Value	28,010	4	28,006
Balance, value at Sep. 30, 2013	4,306,666	905	8,030,508	(3,791,975)	67,103	125
Balance, shares at Sep. 30, 2013		905,089,271
Balance, value at Dec. 31, 2013	4,266,641	909	8,063,517	(3,870,649)	71,128	1,736
Balance, shares at Dec. 31, 2013		909,855,173
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income Loss Attributable To Company Inclusive Of Noncontrolling Interest Excluding Noncontrolling Redeemable Interests	192,539			192,523		16
Net income	192,539
Unrealized gain on investment securities	13,508				13,508
Unrealized (gain) loss on derivatives	(1,659)				(1,659)
Reclassification adjustment from AOCI on derivatives and securities	(42,068)				(42,068)
Distributions declared	(329,144)			(329,144)
Noncontrolling Interest, Increase from Subsidiary Equity Issuance	1,502					1,502
Proceeds from distribution reinvestment plan, value	95,832	14	95,818
Proceeds from distribution reinvestment plan, shares		13,808,589
Share repurchase program, shares		(1,077,829)
Stock Repurchased and Retired During Period, Value	(396,430)							(396,369)	(61)
Stock Repurchased During Period, Shares							(60,761,166)
Stock Repurchased During Period, Value	7,481	1	7,480
Balance, value at Sep. 30, 2014	$ 3,793,240	$ 861	$ 7,755,486	$ (4,007,270)	$ 40,909	$ 3,254
Balance, shares at Sep. 30, 2014		861,824,767