Summary of Significant Accounting Policies and Procedures and Recent Accounting Pronouncements (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 C Corporation	Aug. 31, 2007 C Corporation
Reconciliation of net income available to common stockholders to taxable income
Net income available to common stockholders	$ 114,538,000	$ 132,779,000	$ 106,531,000
Preferred stock dividends	40,918,000	24,253,000	24,253,000
Depreciation and amortization timing differences	45,398,000	32,215,000	23,024,000
Merger-related costs	7,877,000
Excess of redemption value over carrying value of preferred shares redeemed	3,696,000
Tax loss on the sale of real estate less than book gain	(12,559,000)	(7,772,000)	(10,063,000)
Elimination of net revenue and expenses from Crest	444,000	418,000	1,337,000
Compensation deduction per Section 162(m) of the Code	7,599,000	4,896,000	2,915,000
Adjustment for share-based compensation	(351,000)	(622,000)	562,000
Adjustment for straight-line rent and above/below-market lease amortization	(3,899,000)	(1,562,000)	(1,613,000)
Adjustment for acquisition expenses	2,211,000	1,503,000	368,000
Adjustment for an increase in prepaid rent	2,773,000	3,584,000	4,223,000
Other adjustments	1,286,000	(565,000)	(30,000)
Taxable net income, before dividends paid deduction	209,931,000	189,127,000	151,507,000
Acquisition of C corporation
Period over which gain on disposition of property recognized				10 years
Period over which gain on disposition of property will be recognized for the next fiscal year				5 years
Percentage of voting stock acquired					100.00%
Built-in gains on transfer of property				$ 70,300,000