Condensed Consolidated Statements of Equity (USD $) In Thousands, unless otherwise specified	Total	Preferred Stock	Common Stock	Additional Paid-In Capital	Treasury Stock	Distributions in Excess of Net Income	Stockholders' Investment	Nonredeemable Noncontrolling Interests
Beginning Balance at Dec. 31, 2012	$ 642,953	$ 169,602	$ 107,660	$ 690,024	$ (86,840)	$ (260,104)	$ 620,342	$ 22,611
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest	122,702	0	0	0	0	117,862	117,862	4,840
Common stock issued pursuant to:
Director Stock Grants, Value, Share-based Compensation, Net of Forfeitures	544	0	50	494	0	0	544	0
Stock Issued During Period, Value, Stock Options Exercised	(137)	0	25	(162)	0	0	(137)	0
Stock Issued During Period, Value, New Issues	826,529	0	85,507	741,022	0	0	826,529	0
Restricted stock grants, net of amounts withheld for income taxes	(1,179)	0	30	(1,209)	0	0	(1,179)	0
Amortization of stock options and restricted stock, net of forfeitures	1,421	0	(42)	1,463	0	0	1,421	0
Distributions to noncontrolling interests	(25,888)	0	0	0	0	0	0	(25,888)
Preferred Stock Redemption	(74,827)	(74,827)	0	(10,822)	0	10,822	(74,827)	0
Preferred dividends paid	(8,231)	0	0	0	0	(8,231)	(8,231)	0
Common dividends paid	(18,657)	0	0	0	0	(18,657)	(18,657)	0
Ending Balance at Sep. 30, 2013	1,465,230	94,775	193,230	1,420,810	(86,840)	(158,308)	1,463,667	1,563
Beginning Balance at Dec. 31, 2013	1,458,972	94,775	193,236	1,420,951	(86,840)	(164,721)	1,457,401	1,571
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest	29,160	0	0	0	0	28,784	28,784	376
Common stock issued pursuant to:
Director Stock Grants, Value, Share-based Compensation, Net of Forfeitures	653	0	55	598	0	0	653	0
Stock Issued During Period, Value, Stock Options Exercised	(227)	0	40	(267)	0	0	(227)	0
Stock Issued During Period, Value, New Issues	321,912	0	26,700	295,212	0	0	321,912	0
Restricted stock grants, net of amounts withheld for income taxes	(925)	0	53	(978)	0	0	(925)	0
Amortization of stock options and restricted stock, net of forfeitures	1,508	0	(5)	1,513	0	0	1,508	0
Distributions to noncontrolling interests	(369)	0	0	0	0	0	0	(369)
Preferred Stock Redemption	(94,775)	(94,775)	0	3,530	0	(3,530)	(94,775)	0
Preferred dividends paid	(2,955)	0	0	0	0	(2,955)	(2,955)	0
Common dividends paid	(45,351)	0	0	0	0	(45,351)	(45,351)	0
Ending Balance at Sep. 30, 2014	$ 1,667,603	$ 0	$ 220,079	$ 1,720,559	$ (86,840)	$ (187,773)	$ 1,666,025	$ 1,578