Equity Investments (Details 3) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Income Statements:
Rental income	$ 261,661	$ 241,785	$ 768,281	$ 670,396
Operating expenses	(112,577)	(104,683)	(324,760)	(285,703)
Acquisition related costs	(1,066)	(4,805)	(5,002)	(9,722)
General and administrative	(14,592)	(11,692)	(40,266)	(34,275)
Operating income	69,989	54,969	209,913	172,377
Interest and other income	399	320	1,100	1,395
Interest expense	(51,138)	(49,423)	(150,481)	(145,037)
Equity in earnings of investees	2,868	2,768	8,655	8,390
Income before income tax expense	21,898	20,121	67,292	48,612
Income tax (expense) benefit	(1,322)	(307)	(1,906)	(743)
Net income	22,265	28,535	67,425	95,111
GOV
Income Statements:
Rental income	54,083	45,889	154,811	127,224
Operating expenses	(20,433)	(17,121)	(57,798)	(47,443)
Depreciation and amortization	(13,056)	(10,379)	(37,281)	(27,862)
Acquisition related costs	(763)	(1,008)	(1,057)	(2,846)
General and administrative	(3,637)	(2,746)	(9,395)	(7,655)
Operating income	16,194	14,635	49,280	41,418
Interest and other income	7	54	21	89
Interest expense	(4,530)	(3,162)	(12,649)	(8,775)
Equity in earnings of investees	115	28	236	111
Income before income tax expense	11,786	11,555	36,888	32,843
Income tax (expense) benefit	(30)	8	(119)	(94)
Net income	$ 11,756	$ 11,563	$ 36,769	$ 32,749
Weighted average common shares outstanding	47,108	45,322	47,086	42,127
Net income per common share (in dollars per share)	$ 0.25	$ 0.26	$ 0.78	$ 0.78
AIC
Income Statements:
Number of other companies which are shareholders of related party	5		5
Equity method investments, ownership percentage by each of CWH and SIR	12.50%		12.50%