Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013 item	Mar. 31, 2012	Dec. 31, 2012
Segment Reporting
Number of operating segments	4
Number of reportable segments	3
Number of rehabilitation hospitals	2
Segment reporting
Number of previously reportable segments	2
Revenues:
Rental income	$ 114,373	$ 109,505
Residents fees and services	75,056	35,568
Total revenues	189,429	145,073
Expenses:
Depreciation	38,302	33,377
Property operating expenses	74,582	39,334
General and administrative	8,648	7,685
Acquisition related costs	1,903	688
Impairment of assets	1,304	3,071
Total expenses	124,739	84,155
Operating income (loss)	64,690	60,918
Interest and other income	173	482
Interest expense	(29,564)	(28,889)
Equity in earnings of an investee	76	45
Income before income tax expense	35,375	32,556
Income tax expense	(140)	(204)
Net income	35,235	32,352
Total assets	4,811,269		4,748,002
TRS
Segment reporting
Number of properties transferred	10
Triple Net Senior Living Communities
Revenues:
Rental income	56,765	58,824
Total revenues	56,765	58,824
Expenses:
Depreciation	16,917	17,191
Total expenses	16,917	17,191
Operating income (loss)	39,848	41,633
Interest expense	(6,463)	(10,245)
Income before income tax expense	33,385	31,388
Net income	33,385	31,388
Total assets	1,910,293	2,003,386
Managed Senior Living Communities
Revenues:
Residents fees and services	75,056	35,568
Total revenues	75,056	35,568
Expenses:
Depreciation	6,849	3,706
Property operating expenses	57,904	25,499
Total expenses	64,753	29,205
Operating income (loss)	10,303	6,363
Interest expense	(3,068)	(2,933)
Income before income tax expense	7,235	3,430
Net income	7,235	3,430
Total assets	954,155	730,879
MOBs
Revenues:
Rental income	53,204	46,261
Total revenues	53,204	46,261
Expenses:
Depreciation	13,588	11,532
Property operating expenses	16,678	13,835
Impairment of assets	1,304	3,071
Total expenses	31,570	28,438
Operating income (loss)	21,634	17,823
Interest expense	(1,348)	(412)
Income before income tax expense	20,286	17,411
Net income	20,286	17,411
Total assets	1,522,646	644,811
All Other Operations
Revenues:
Rental income	4,404	4,420
Total revenues	4,404	4,420
Expenses:
Depreciation	948	948
General and administrative	8,648	7,685
Acquisition related costs	1,903	688
Total expenses	11,499	9,321
Operating income (loss)	(7,095)	(4,901)
Interest and other income	173	482
Interest expense	(18,685)	(15,299)
Equity in earnings of an investee	76	45
Income before income tax expense	(25,531)	(19,673)
Income tax expense	(140)	(204)
Net income	(25,671)	(19,877)
Total assets	424,175	1,004,745
Consolidated
Revenues:
Rental income	114,373	109,505
Residents fees and services	75,056	35,568
Total revenues	189,429	145,073
Expenses:
Depreciation	38,302	33,377
Property operating expenses	74,582	39,334
General and administrative	8,648	7,685
Acquisition related costs	1,903	688
Impairment of assets	1,304	3,071
Total expenses	124,739	84,155
Operating income (loss)	64,690	60,918
Interest and other income	173	482
Interest expense	(29,564)	(28,890)
Equity in earnings of an investee	76	46
Income before income tax expense	35,375	32,556
Income tax expense	(140)	(204)
Net income	35,235	32,352
Total assets	$ 4,811,269	$ 4,383,821