Fair Value Measurements - Additional Information (Details) $ in Thousands		3 Months Ended
	Jan. 01, 2019 USD ($) community	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities		$ 83,517		$ 14,855
Debt		3,642,997		3,640,180
Property, plant and equipment and leasehold intangibles, net			$ 40,800
ASU 2016-02
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Operating lease right-of-use asset, number of communities impaired | community	25
Operating lease right-of-use assets	$ 56,600
Reported Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt		3,600,000		$ 3,600,000
Assisted Living
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill impairment			351,700
Interest Income
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gains related to trading securities		300	$ 600
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities		$ 83,500