Segment Reporting (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2016 USD ($) segment	Mar. 31, 2015 USD ($)	Dec. 31, 2015 USD ($)
Segment reporting
Number of operating segments | segment	4
Number of reportable segments | segment	3
Revenues:
Rental income	$ 161,421	$ 145,784
Residents fees and services	96,954	82,793
Total revenues	258,375	228,577
Expenses:
Property operating expenses	97,949	85,794
Depreciation	71,223	53,707
General and administrative	10,863	10,574
Acquisition related costs	439	1,158
Impairment of assets	7,390
Total expenses	187,864	151,233
Operating income	70,511	77,344
Interest and other income	64	75
Interest expense	(39,280)	(35,942)
Loss on early extinguishment of debt	(6)	(1,409)
Income (loss) before income tax expense and equity in earnings of an investee	31,289	40,068
Income tax expense	(94)	(110)
Equity in earnings of an investee	77	72
Income (loss) from continuing operations	31,272	40,030
Discontinued Operations:
Loss from discontinued operations		(241)
Net income	31,272	39,789
Total assets	7,154,151	7,160,090	$ 7,160,090
Triple Net Leased Senior Living Communities
Revenues:
Rental income	65,308	55,251
Total revenues	65,308	55,251
Expenses:
Property operating expenses	363
Depreciation	19,401	15,125
Impairment of assets	4,391
Total expenses	24,155	15,125
Operating income	41,153	40,126
Interest expense	(6,382)	(5,985)
Income (loss) before income tax expense and equity in earnings of an investee	34,771	34,141
Income (loss) from continuing operations		34,141
Discontinued Operations:
Net income	34,771	34,141
Total assets	2,238,090	2,251,212
Managed Senior Living Communities
Revenues:
Residents fees and services	96,954	82,793
Total revenues	96,954	82,793
Expenses:
Property operating expenses	72,178	62,403
Depreciation	20,018	8,460
Total expenses	92,196	70,863
Operating income	4,758	11,930
Interest expense	(2,564)	(2,019)
Loss on early extinguishment of debt	(6)
Income (loss) before income tax expense and equity in earnings of an investee	2,188	9,911
Income (loss) from continuing operations		9,911
Discontinued Operations:
Net income	2,188	9,911
Total assets	1,252,520	1,260,425
MOBs
Revenues:
Rental income	91,582	86,001
Total revenues	91,582	86,001
Expenses:
Property operating expenses	25,408	23,391
Depreciation	30,856	29,174
Impairment of assets	2,999
Total expenses	59,263	52,565
Operating income	32,319	33,436
Interest expense	(953)	(1,768)
Income (loss) before income tax expense and equity in earnings of an investee	31,366	31,668
Income (loss) from continuing operations		31,668
Discontinued Operations:
Loss from discontinued operations		(241)
Net income	31,366	31,427
Total assets	3,359,385	3,362,214
All Other Operations
Revenues:
Rental income	4,531	4,532
Total revenues	4,531	4,532
Expenses:
Depreciation	948	948
General and administrative	10,863	10,574
Acquisition related costs	439	1,158
Total expenses	12,250	12,680
Operating income	(7,719)	(8,148)
Interest and other income	64	75
Interest expense	(29,381)	(26,170)
Loss on early extinguishment of debt		(1,409)
Income (loss) before income tax expense and equity in earnings of an investee	(37,036)	(35,652)
Income tax expense	(94)	(110)
Equity in earnings of an investee	77	72
Income (loss) from continuing operations		(35,690)
Discontinued Operations:
Net income	(37,053)	(35,690)
Total assets	$ 304,156	$ 286,239