Supplemental Disclosure of Cash Flow Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Supplemental Cash Flow Information [Abstract]
Interest paid	$ 59,479	$ 62,107
Income taxes paid, net of refunds	957	606
Net cash paid	69,385	60,055
Gain (loss) on debt modification and extinguishment, net	19,181	(67)
Investment in unconsolidated ventures	(268)	(3,986)
Loss (gain) on sale of assets, net	(372,839)	702
Prepaid expenses and other assets, net	(1,696)	12,358
Loss (gain) on facility lease termination and modification, net	0	209
Additions to property, plant and equipment and leasehold improvements
Supplemental Cash Flow Information [Abstract]
Net cash paid	69,385	60,055
Trade accounts payable	(898)	184
Acquisition of communities from Healthpeak
Supplemental Cash Flow Information [Abstract]
Property, plant and equipment and leasehold intangibles, net	286,734	0
Operating lease right-of-use assets	63,285	0
Financing lease obligations	129,196	0
Operating lease obligations	74,335	0
Gain (loss) on debt modification and extinguishment, net	19,731	0
Net cash paid	407,249	0
Acquisition of assets, net of related payables and cash received
Supplemental Cash Flow Information [Abstract]
Property, plant and equipment and leasehold intangibles, net	179	32,126
Net cash paid	39,439	27,330
Financing lease right-of-use assets	39,260	0
Other intangibles assets, net	0	(4,796)
Proceeds from Sale of CCRC Venture, net
Supplemental Cash Flow Information [Abstract]
Investment in unconsolidated ventures	(14,848)	0
Current portion of long-term debt	34,706	0
Accrued expenses	(5,025)	0
Other liabilities	(60,748)	0
Loss (gain) on sale of assets, net	(370,745)	0
Net cash received	(295,164)	0
Proceeds from sale of assets, net
Supplemental Cash Flow Information [Abstract]
Other liabilities	(824)	78
Loss (gain) on sale of assets, net	(2,094)	702
Prepaid expenses and other assets, net	(1,261)	(231)
Assets held for sale	(5,274)	(29,550)
Property, plant and equipment and leasehold intangibles, net	0	(457)
Net cash received	(9,453)	(29,458)
Purchase of Treasury Stock
Supplemental Cash Flow Information [Abstract]
Treasury stock	0	288
Accounts payable	0	(288)
Net	0	0
Assets designated as held for sale
Supplemental Cash Flow Information [Abstract]
Assets held for sale	0	5,249
Net	0	0
Property, plant and equipment and leasehold intangibles, net	0	5,249
Healthpeak master lease modification
Supplemental Cash Flow Information [Abstract]
Operating lease right-of-use assets	88,044	0
Financing lease obligations	70,874	0
Operating lease obligations	(101,456)	0
Net	0	0
Property, plant and equipment and leasehold intangibles, net	(57,462)	0
Noncash lease termination and modification, net
Supplemental Cash Flow Information [Abstract]
Financing lease obligations	9,516	0
Other liabilities	(75)	(224)
Prepaid expenses and other assets, net	0	160
Property, plant and equipment and leasehold intangibles, net	9,441	(175)
Net	0	0
Loss (gain) on facility lease termination and modification, net	0	209
Non-development | Additions to property, plant and equipment and leasehold improvements
Supplemental Cash Flow Information [Abstract]
Net cash paid	60,556	54,602
Development | Additions to property, plant and equipment and leasehold improvements
Supplemental Cash Flow Information [Abstract]
Net cash paid	3,900	5,269
Non-development - reimbursable | Additions to property, plant and equipment and leasehold improvements
Supplemental Cash Flow Information [Abstract]
Net cash paid	$ 5,827	$ 0