Equity Investments (Details 2) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2010	Dec. 31, 2009
Balance Sheets:
Real estate properties, net	$ 6,259,901	$ 5,506,997
Acquired real estate leases, net	360,293	233,913
Cash and cash equivalents	210,673	194,040	174,723	18,204
Rents receivable, net	212,737	191,237
Other assets, net	182,259	171,380
Total assets	7,458,190	6,588,539
Revolving credit facility	235,000
Mortgage notes payable	633,935	351,526
Assumed real estate lease obligations, net	72,619	65,940
Other liabilities	148,525	123,842
Total liabilities and shareholders' equity	7,458,190	6,588,539
GOV
Balance Sheets:
Real estate properties, net	1,104,560	846,447
Acquired real estate leases, net	103,901	60,097
Cash and cash equivalents	5,724	2,437
Rents receivable, net	22,096	19,200
Other assets, net	30,387	23,107
Total assets	1,266,668	951,288
Revolving credit facility	282,500	118,000
Mortgage notes payable	45,608	46,428
Assumed real estate lease obligations, net	11,853	13,679
Other liabilities	28,518	15,784
Shareholders' equity	898,189	757,397
Total liabilities and shareholders' equity	$ 1,266,668	$ 951,288