CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Cash flows from operating activities:
Net income	$ 78,957	$ 91,248
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation	115,274	104,487
Amortization of deferred financing fees and debt discounts	4,559	4,494
Straight line rental income	(5,256)	(10,248)
Amortization of acquired real estate leases and other intangible assets	2,793	746
Loss on early extinguishment of debt	797	6,349
Impairment of assets	33,571	3,071
Loss on lease terminations		104
(Gain) loss on sale of properties	(1,141)	101
Equity in earnings of an investee	(219)	(236)
Change in assets and liabilities:
Restricted cash	(614)	(4,249)
Other assets	569	13,978
Accrued interest	6,006	(263)
Other liabilities	12,884	29,430
Cash provided by operating activities	248,180	239,012
Cash flows from investing activities:
Real estate acquisitions and deposits	(148,775)	(255,769)
Real estate improvements	(36,820)	(29,645)
Principal payments on loan receivable		38,000
Proceeds from sale of properties	2,550	1,041
Cash used for investing activities	(183,045)	(246,373)
Cash flows from financing activities:
Proceeds from issuance of common shares, net	261,813	287,052
Proceeds from issuance of unsecured senior notes, net of discount		350,000
Proceeds from borrowings on revolving credit facility	160,000	509,000
Repayments of borrowings on revolving credit facility	(225,000)	(454,000)
Redemption of senior notes		(225,000)
Repayment of other debt	(33,261)	(259,400)
Payment of deferred financing fees	(3,252)	(12,186)
Distributions to shareholders	(215,559)	(190,680)
Cash (used for) provided by financing activities	(55,259)	4,786
Increase (decrease) in cash and cash equivalents	9,876	(2,575)
Cash and cash equivalents at beginning of period	42,382	23,560
Cash and cash equivalents at end of period	52,258	20,985
Supplemental cash flow information:
Interest paid	79,552	83,195
Income taxes paid	536	389
Non-cash investing activities:
Acquisitions funded by assumed debt	(12,266)	(112,153)
Non-cash financing activities:
Assumption of mortgage notes payable	12,266	112,153
Issuance of common shares	$ 2,538	$ 2,138