Segment Reporting (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) segment	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Segment reporting
Number of reportable segments | segment	2
Total revenues	$ 1,632,026	$ 1,040,155	$ 1,117,164
Expenses:
Property operating expenses	1,236,357	489,070	451,581
Depreciation and amortization	270,147	289,025	286,235
General and administrative	30,593	37,028	85,885
Acquisition and certain other transaction related costs	814	13,102	194
Impairment of assets	106,972	115,201	66,346
Total expenses	1,644,883	943,426	890,241
Gain on sale of properties	6,487	39,696	261,916
Dividend income	0	1,846	2,901
Gains and losses on equity securities, net	34,106	(41,898)	(20,724)
Interest and other income	18,221	941	667
Interest expense	(201,483)	(180,112)	(179,287)
Gain on lease termination	22,896	0	0
Loss on early extinguishment of debt	(427)	(44)	(22)
Income (loss) from continuing operations before income tax expense and equity in earnings of an investee	(133,057)	(82,842)	292,374
Income tax expense	(1,250)	(436)	(476)
Equity in earnings of an investee	0	400	516
Net (loss) income	(134,307)	(82,878)	292,414
Net income attributable to noncontrolling interest	(5,146)	(5,356)	(5,542)
Net income (loss)	(139,453)	(88,234)	286,872
Total assets	6,476,424	6,653,826	7,160,426
Non-Segment
Segment reporting
Total revenues	43,850	63,644	75,206
Expenses:
Property operating expenses	0	0	0
Depreciation and amortization	11,702	18,777	23,455
General and administrative	30,593	37,028	85,885
Acquisition and certain other transaction related costs	814	13,102	194
Impairment of assets	0	6,344	19,549
Total expenses	43,109	75,251	129,083
Gain on sale of properties	4,517	17,872	258,217
Dividend income		1,846	2,901
Gains and losses on equity securities, net	34,106	(41,898)	(20,724)
Interest and other income	736	941	667
Interest expense	(175,072)	(152,655)	(149,713)
Gain on lease termination	22,896
Loss on early extinguishment of debt	(26)	(27)	76
Income (loss) from continuing operations before income tax expense and equity in earnings of an investee	(112,102)	(185,528)	37,547
Income tax expense	(1,250)	(436)	(476)
Equity in earnings of an investee		400	516
Net (loss) income	(113,352)	(185,564)	37,587
Net income attributable to noncontrolling interest	0	0	0
Net income (loss)	(113,352)	(185,564)	37,587
Total assets	471,565	443,260	831,512
Office Portfolio | Operating Segments
Segment reporting
Total revenues	383,365	405,016	412,813
Expenses:
Property operating expenses	129,756	132,348	127,732
Depreciation and amortization	129,321	137,611	141,477
General and administrative	0	0	0
Acquisition and certain other transaction related costs	0	0	0
Impairment of assets	8,558	43,035	46,797
Total expenses	267,635	312,994	316,006
Gain on sale of properties	2,597	6,617	0
Dividend income		0	0
Gains and losses on equity securities, net	0	0	0
Interest and other income	0	0	0
Interest expense	(24,188)	(24,399)	(24,360)
Gain on lease termination	0
Loss on early extinguishment of debt	(401)	0	0
Income (loss) from continuing operations before income tax expense and equity in earnings of an investee	93,738	74,240	72,447
Income tax expense	0	0	0
Equity in earnings of an investee		0	0
Net (loss) income	93,738	74,240	72,447
Net income attributable to noncontrolling interest	(5,146)	(5,356)	(5,542)
Net income (loss)	88,592	68,884	66,905
Total assets	3,092,289	3,165,577	3,344,581
SHOP | Operating Segments
Segment reporting
Total revenues	1,204,811	571,495	629,145
Expenses:
Property operating expenses	1,106,601	356,722	323,849
Depreciation and amortization	129,124	132,637	121,303
General and administrative	0	0	0
Acquisition and certain other transaction related costs	0	0	0
Impairment of assets	98,414	65,822	0
Total expenses	1,334,139	555,181	445,152
Gain on sale of properties	(627)	15,207	3,699
Dividend income		0	0
Gains and losses on equity securities, net	0	0	0
Interest and other income	17,485	0	0
Interest expense	(2,223)	(3,058)	(5,214)
Gain on lease termination	0
Loss on early extinguishment of debt	0	(17)	(98)
Income (loss) from continuing operations before income tax expense and equity in earnings of an investee	(114,693)	28,446	182,380
Income tax expense	0	0	0
Equity in earnings of an investee		0	0
Net (loss) income	(114,693)	28,446	182,380
Net income attributable to noncontrolling interest	0	0	0
Net income (loss)	(114,693)	28,446	182,380
Total assets	2,912,570	3,044,989	2,984,333
Provider Relief Fund, CARES Act	19,961
Provider Relief Fund, expected HHS return, CARES Act	2,476
Rental income
Segment reporting
Total revenues	427,215	606,558	700,641
Rental income | Non-Segment
Segment reporting
Total revenues	43,850	63,644	75,206
Rental income | Office Portfolio | Operating Segments
Segment reporting
Total revenues	383,365	405,016	412,813
Rental income | SHOP | Operating Segments
Segment reporting
Total revenues	0	137,898	212,622
Residents fees and services
Segment reporting
Total revenues	1,204,811	433,597	416,523
Residents fees and services | Non-Segment
Segment reporting
Total revenues	0	0	0
Residents fees and services | Office Portfolio | Operating Segments
Segment reporting
Total revenues	0	0	0
Residents fees and services | SHOP | Operating Segments
Segment reporting
Total revenues	$ 1,204,811	$ 433,597	$ 416,523