Fair Value Measurements - Narrative (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	$ 14,855,000				$ 291,796,000				$ 14,855,000	$ 291,796,000
Gains related to trading securities									1,400,000	600,000
Debt	4,514,656,000				5,142,291,000				4,514,656,000	5,142,291,000
Goodwill	154,131,000				505,783,000				154,131,000	505,783,000
Goodwill and asset impairment	37,927,000	$ 5,500,000	$ 16,103,000	$ 430,363,000	18,966,000	$ 368,551,000	$ 1,559,000	$ 20,706,000	489,893,000	409,782,000	$ 248,515,000
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	14,900,000								14,900,000
Reported Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt	3,600,000,000				3,900,000,000				3,600,000,000	3,900,000,000
Assisted Living and Memory Care
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amount of carrying amount in excess of fair value				351,700,000		205,000,000
Goodwill impairment				$ 351,700,000		$ 205,000,000
Goodwill	0				351,652,000				0	351,652,000
Independent Living
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill	27,321,000				27,321,000				27,321,000	27,321,000
Health Care Services
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill	$ 126,810,000				$ 126,810,000				126,810,000	126,810,000
Goodwill and asset impairment									9,100,000	14,600,000
Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill impairment									351,700,000	205,000,000	0
Property, plant and equipment impairment									78,000,000	164,400,000	166,200,000
Equity method investment impairment									33,400,000	25,800,000	36,800,000
Goodwill and asset impairment									489,900,000	409,800,000	248,500,000
Impairment of assets held for sale									$ 15,600,000	0	15,800,000
Minimum | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Capitalization rate	6.50%								6.50%
Maximum | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Capitalization rate	9.00%								9.00%
Health care licenses
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill and asset impairment									$ 9,100,000	$ 14,600,000
Community purchase options
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill and asset impairment											$ 28,200,000