Fair Value Measurements - Additional Information (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	$ 291,796,000				$ 0				$ 291,796,000	$ 0
Gains related to trading securities									600,000
Debt	5,142,291,000				6,045,167,000				5,142,291,000	6,045,167,000
Goodwill and asset impairment	18,966,000	$ 368,551,000	$ 1,559,000	$ 20,706,000	221,877,000	$ 19,111,000	$ 4,152,000	$ 3,375,000	409,782,000	248,515,000	$ 57,941,000
Investment in unconsolidated ventures (Note 6)									25,800,000	36,800,000
Impairment of assets held for sale									0	15,800,000	33,600,000
Reported Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt	3,900,000,000				$ 3,600,000,000				3,900,000,000	3,600,000,000
Buildings and improvements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill and asset impairment									164,400,000	166,200,000	$ 23,400,000
Assisted Living
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amount of carrying amount in excess of fair value		205,000,000
Goodwill (Note 8)		205,000,000
Brookdale Ancillary Services
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill and asset impairment		13,700,000
Health care licenses
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill and asset impairment		$ 13,700,000
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	$ 291,800,000								$ 291,800,000
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%
Community purchase options
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill and asset impairment										$ 28,200,000