Segment Reporting (Details) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Jun. 30, 2019 USD ($) segment	Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment					4
Number of reportable segments | segment					3
Revenues:
Total revenues	$ 262,003		$ 277,202		$ 528,289	$ 552,972
Expenses:
Property operating expenses	120,193		110,056		237,415	218,154
Depreciation and amortization	73,924		72,300		146,154	142,639
General and administrative	8,867		29,078		18,683	54,196
Acquisition and certain other transaction related costs	903		67		8,717	87
Impairment of assets	2,213		548		8,419	548
Total expenses	206,100		212,049		419,388	415,624
Gain on sale of properties	17,832		80,762		17,710	261,916
Dividend income	923		659		1,846	1,318
Unrealized gain (loss) on equity securities	(64,448)		23,265		(41,516)	50,506
Interest and other income	238		60		352	114
Interest expense	(46,412)		(44,813)		(92,023)	(88,365)
Loss on early extinguishment of debt	(17)		0		(17)	(130)
(Loss) income from continuing operations before income tax benefit (expense) and equity in earnings of an investee	(35,981)		125,086		(4,747)	362,707
Income tax benefit	35		(105)		(99)	(365)
Equity in earnings of an investee	130		7		534	51
Net (loss) income	(35,816)	$ 31,504	124,988	$ 237,405	(4,312)	362,393
Net income attributable to noncontrolling interest	(1,413)		(1,401)		(2,835)	(2,784)
Net income (loss) attributable to common shareholders	(37,229)		123,587		(7,147)	359,609
Assets	7,098,710				7,098,710		$ 7,160,426
MOBs
Revenues:
Total revenues	104,385		103,854		207,606	205,005
Expenses:
Property operating expenses	32,525		31,183		64,702	62,121
Depreciation and amortization	35,037		36,326		71,138	70,711
General and administrative	0		0		0	0
Acquisition and certain other transaction related costs	0		0		0	0
Impairment of assets	96		0		96	0
Total expenses	67,658		67,509		135,936	132,832
Gain on sale of properties	2,625		0		2,503	0
Dividend income	0		0		0	0
Unrealized gain (loss) on equity securities	0		0		0	0
Interest and other income	0		0		0	0
Interest expense	(5,988)		(6,113)		(12,018)	(12,022)
Loss on early extinguishment of debt	0				0	0
(Loss) income from continuing operations before income tax benefit (expense) and equity in earnings of an investee	33,364		30,232		62,155	60,151
Income tax benefit	0		0		0	0
Equity in earnings of an investee	0		0		0	0
Net (loss) income	33,364		30,232		62,155	60,151
Net income attributable to noncontrolling interest	(1,413)		(1,401)		(2,835)	(2,784)
Net income (loss) attributable to common shareholders	31,951		28,831		59,320	57,367
Assets	3,294,265				3,294,265		3,344,581
Triple Net Leased Senior Living Communities
Revenues:
Total revenues	44,037		66,113		94,357	134,088
Expenses:
Property operating expenses	0		0		0	0
Depreciation and amortization	21,457		20,186		40,879	40,381
General and administrative	0		0		0	0
Acquisition and certain other transaction related costs	0		0		0	0
Impairment of assets	2,117		548		8,323	548
Total expenses	23,574		20,734		49,202	40,929
Gain on sale of properties	15,207		80,762		15,207	261,916
Dividend income	0		0		0	0
Unrealized gain (loss) on equity securities	0		0		0	0
Interest and other income	0		0		0	0
Interest expense	(170)		(565)		(408)	(1,136)
Loss on early extinguishment of debt	0				0	0
(Loss) income from continuing operations before income tax benefit (expense) and equity in earnings of an investee	35,500		125,576		59,954	353,939
Income tax benefit	0		0		0	0
Equity in earnings of an investee	0		0		0	0
Net (loss) income	35,500		125,576		59,954	353,939
Net income attributable to noncontrolling interest	0		0		0	0
Net income (loss) attributable to common shareholders	35,500		125,576		59,954	353,939
Assets	1,968,936				1,968,936		2,044,939
Managed Senior Living Communities
Revenues:
Total revenues	108,906		102,617		216,951	204,659
Expenses:
Property operating expenses	87,668		78,873		172,713	156,033
Depreciation and amortization	16,483		14,841		32,243	29,652
General and administrative	0		0		0	0
Acquisition and certain other transaction related costs	0		0		0	0
Impairment of assets	0		0		0	0
Total expenses	104,151		93,714		204,956	185,685
Gain on sale of properties	0		0		0	0
Dividend income	0		0		0	0
Unrealized gain (loss) on equity securities	0		0		0	0
Interest and other income	0		0		0	0
Interest expense	(730)		(1,256)		(1,550)	(2,583)
Loss on early extinguishment of debt	(17)				(17)	(130)
(Loss) income from continuing operations before income tax benefit (expense) and equity in earnings of an investee	4,008		7,647		10,428	16,261
Income tax benefit	0		0		0	0
Equity in earnings of an investee	0		0		0	0
Net (loss) income	4,008		7,647		10,428	16,261
Net income attributable to noncontrolling interest	0		0		0	0
Net income (loss) attributable to common shareholders	4,008		7,647		10,428	16,261
Assets	1,454,742				1,454,742		1,395,657
All Other Operations
Revenues:
Total revenues	4,675		4,618		9,375	9,220
Expenses:
Property operating expenses	0		0		0	0
Depreciation and amortization	947		947		1,894	1,895
General and administrative	8,867		29,078		18,683	54,196
Acquisition and certain other transaction related costs	903		67		8,717	87
Impairment of assets	0		0		0	0
Total expenses	10,717		30,092		29,294	56,178
Gain on sale of properties	0		0		0	0
Dividend income	923		659		1,846	1,318
Unrealized gain (loss) on equity securities	(64,448)		23,265		(41,516)	50,506
Interest and other income	238		60		352	114
Interest expense	(39,524)		(36,879)		(78,047)	(72,624)
Loss on early extinguishment of debt	0				0	0
(Loss) income from continuing operations before income tax benefit (expense) and equity in earnings of an investee	(108,853)		(38,369)		(137,284)	(67,644)
Income tax benefit	35		(105)		(99)	(365)
Equity in earnings of an investee	130		7		534	51
Net (loss) income	(108,688)		(38,467)		(136,849)	(67,958)
Net income attributable to noncontrolling interest	0		0		0	0
Net income (loss) attributable to common shareholders	(108,688)		(38,467)		(136,849)	(67,958)
Assets	380,767				380,767		$ 375,249
Rental income
Revenues:
Total revenues	153,097		174,585		311,338	348,313
Rental income | MOBs
Revenues:
Total revenues	104,385		103,854		207,606	205,005
Rental income | Triple Net Leased Senior Living Communities
Revenues:
Total revenues	44,037		66,113		94,357	134,088
Rental income | Managed Senior Living Communities
Revenues:
Total revenues	0		0		0	0
Rental income | All Other Operations
Revenues:
Total revenues	4,675		4,618		9,375	9,220
Residents fees and services
Revenues:
Total revenues	108,906		102,617		216,951	204,659
Residents fees and services | MOBs
Revenues:
Total revenues	0		0		0	0
Residents fees and services | Triple Net Leased Senior Living Communities
Revenues:
Total revenues	0		0		0	0
Residents fees and services | Managed Senior Living Communities
Revenues:
Total revenues	108,906		102,617		216,951	204,659
Residents fees and services | All Other Operations
Revenues:
Total revenues	$ 0		$ 0		$ 0	$ 0