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	57,673	0	0	0	0	56,703	56,703	970
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	(121)	0	22	(143)	0	0	(121)	0
Stock Issued During Period, Value, New Issues	165,100	0	16,507	148,593	0	0	165,100	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	987	0	(11)	998	0	0	987	0
Distributions to noncontrolling interests	(942)	0	0	0	0	0	0	(942)
Preferred Stock Redemption	(74,827)	(74,827)	0	(10,822)	0	10,822	(74,827)	0
Preferred dividends paid	(6,454)	0	0	0	0	(6,454)	(6,454)	0
Common dividends paid	(10,120)	0	0	0	0	(10,120)	(10,120)	0
Ending Balance at Jun. 30, 2013	773,614	94,775	124,258	827,935	(86,840)	(209,153)	750,975	22,639
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	9,748	0	0	0	0	9,464	9,464	284
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	(20)	0	3	(23)	0	0	(20)	0
Stock Issued During Period, Value, New Issues	98,519	0	8,700	89,819	0	0	98,519	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	1,059	0	(3)	1,062	0	0	1,059	0
Distributions to noncontrolling interests	(281)	0	0	0	0	0	0	(281)
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	(29,115)	0	0	0	0	(29,115)	(29,115)	0
Ending Balance at Jun. 30, 2014	$ 1,440,880	$ 0	$ 202,044	$ 1,514,959	$ (86,840)	$ (190,857)	$ 1,439,306	$ 1,574