Segment Reporting - Income Statements (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenues:
Total revenues	$ 362,724	$ 442,467
Expenses:
Property operating expenses	287,391	316,585
Depreciation and amortization	66,153	68,430
General and administrative	7,542	8,832
Impairment of assets	(174)	11,234
Total expenses	360,912	405,744
Acquisition and certain other transaction related costs	0	663
Gain (loss) on sale of properties	(122)	2,782
Gains (losses) on equity securities, net	(8,339)	(9,943)
Interest and other income	2,835	138
Interest expense	(60,091)	(41,650)
Gain on lease termination	0	22,896
Loss on early extinguishment of debt	(2,040)	(246)
Income (loss) from continuing operations before income tax expense	(65,945)	10,700
Income tax (expense) benefit	(238)	443
Net income (loss)	(66,183)	11,143
Net income attributable to noncontrolling interest	(1,322)	(1,408)
Net income (loss) attributable to common shareholders	(67,505)	9,735
Operating Segments | Office Portfolio
Revenues:
Total revenues	93,323	98,770
Expenses:
Property operating expenses	31,293	32,706
Depreciation and amortization	31,938	32,163
General and administrative	0	0
Impairment of assets	0	6,218
Total expenses	63,231	71,087
Acquisition and certain other transaction related costs		0
Gain (loss) on sale of properties	(122)	2,782
Gains (losses) on equity securities, net	0	0
Interest and other income	0	0
Interest expense	(5,939)	(6,052)
Gain on lease termination		0
Loss on early extinguishment of debt	0	(246)
Income (loss) from continuing operations before income tax expense	24,031	24,167
Income tax (expense) benefit	0	0
Net income (loss)	24,031	24,167
Net income attributable to noncontrolling interest	(1,322)	(1,408)
Net income (loss) attributable to common shareholders	22,709	22,759
Operating Segments | SHOP
Revenues:
Total revenues	259,966	331,969
Expenses:
Property operating expenses	256,098	283,879
Depreciation and amortization	31,361	33,042
General and administrative	0	0
Impairment of assets	(174)	5,016
Total expenses	287,285	321,937
Acquisition and certain other transaction related costs		0
Gain (loss) on sale of properties	0	0
Gains (losses) on equity securities, net	0	0
Interest and other income	2,433	0
Interest expense	(528)	(564)
Gain on lease termination		0
Loss on early extinguishment of debt	0	0
Income (loss) from continuing operations before income tax expense	(25,414)	9,468
Income tax (expense) benefit	0	0
Net income (loss)	(25,414)	9,468
Net income attributable to noncontrolling interest	0	0
Net income (loss) attributable to common shareholders	(25,414)	9,468
Non-Segment
Revenues:
Total revenues	9,435	11,728
Expenses:
Property operating expenses	0	0
Depreciation and amortization	2,854	3,225
General and administrative	7,542	8,832
Impairment of assets	0	0
Total expenses	10,396	12,720
Acquisition and certain other transaction related costs		663
Gain (loss) on sale of properties	0	0
Gains (losses) on equity securities, net	(8,339)	(9,943)
Interest and other income	402	138
Interest expense	(53,624)	(35,034)
Gain on lease termination		22,896
Loss on early extinguishment of debt	(2,040)	0
Income (loss) from continuing operations before income tax expense	(64,562)	(22,935)
Income tax (expense) benefit	(238)	443
Net income (loss)	(64,800)	(22,492)
Net income attributable to noncontrolling interest	0	0
Net income (loss) attributable to common shareholders	(64,800)	(22,492)
Rental income
Revenues:
Total revenues	102,758	110,498
Rental income | Operating Segments | Office Portfolio
Revenues:
Total revenues	93,323	98,770
Rental income | Operating Segments | SHOP
Revenues:
Total revenues	0	0
Rental income | Non-Segment
Revenues:
Total revenues	9,435	11,728
Residents fees and services
Revenues:
Total revenues	259,966	331,969
Residents fees and services | Operating Segments | Office Portfolio
Revenues:
Total revenues	0	0
Residents fees and services | Operating Segments | SHOP
Revenues:
Total revenues	259,966	331,969
Residents fees and services | Non-Segment
Revenues:
Total revenues	$ 0	$ 0