Master Transactions and Cooperation Agreement with Brookdale (Details) $ in Thousands		1 Months Ended					3 Months Ended					12 Months Ended
	Nov. 01, 2017 USD ($) property	Apr. 30, 2018 USD ($) property	Mar. 31, 2018 USD ($)	Jan. 31, 2018 USD ($) property	Dec. 31, 2017 USD ($)	Mar. 31, 2017 USD ($) facility	Dec. 31, 2018 USD ($) property facility	Sep. 30, 2018 facility	Jun. 30, 2018 facility	Mar. 31, 2018 facility	Dec. 31, 2017 USD ($) property	Dec. 31, 2018 USD ($) property	Dec. 31, 2017 USD ($) facility	Dec. 31, 2016 USD ($) facility	Jan. 01, 2018 USD ($) property
Real Estate Properties [Line Items]
Percentage of voting interest acquired	10.00%
Consideration transferred | $	$ 95,000
Payments to acquire additional interest in subsidiaries | $			$ 63,000		$ 32,000
Proceeds from sale of buildings | $												$ 335,709	$ 462,242	$ 0
Management fee rate													5.00%
Operating expenses | $												$ 705,038	$ 666,251	738,399
RIDEA Facilities
Real Estate Properties [Line Items]
Ownership percentage (as a percent)													90.00%
Assets Leased to Others
Real Estate Properties [Line Items]
Number of properties disposed (in properties)							19
Number of assets sold or transitioned (in properties)												37
Assets Leased to Others | RIDEA Facilities
Real Estate Properties [Line Items]
Number of real estate properties (in properties)	58
Proceeds from sale of buildings | $							$ 377,000
Senior housing triple-net
Real Estate Properties [Line Items]
Total consideration for disposition of real estate | $						$ 1,125,000								$ 88,000
Number of properties disposed (in properties) | facility						64			2				4	7
Senior housing triple-net | Assets Leased to Others
Real Estate Properties [Line Items]
Number of real estate properties (in properties)	78
Right to sell, or transition, number of properties (in properties)							32					32
Rent concessions | $															$ 5,000
Number of properties with rent concessions (in properties)															3
Number of assets to be sold (in properties)	2
Total consideration for disposition of real estate | $	$ 35,000
Number of properties disposed (in properties)							11
Number of assets sold or transitioned (in properties)												17
Reduction in rental and related revenues | $											$ 20,000
Fair value inputs (in properties)											32
SHOP
Real Estate Properties [Line Items]
Total consideration for disposition of real estate | $														$ 41,000
Number of properties disposed (in properties) | facility							2	11	8	2			5	3
SHOP | Assets Leased to Others
Real Estate Properties [Line Items]
Number of assets sold or transitioned (in properties)												20
SHOP | Assets Leased to Others | RIDEA Facilities
Real Estate Properties [Line Items]
Number of real estate properties (in properties)	36
Number of assets to be sold (in properties)	4
Total consideration for disposition of real estate | $	$ 240,000
Number of properties disposed (in properties)		3		1			8
Proceeds from sale of productive assets | $		$ 208,000		$ 32,000
SHOP | Assets Under Management Agreements
Real Estate Properties [Line Items]
Fair value inputs (in properties)											36
Minimum
Real Estate Properties [Line Items]
EBITDAR growth rates													0.00%
Maximum
Real Estate Properties [Line Items]
EBITDAR growth rates													3.00%
Discount rate
Real Estate Properties [Line Items]
Real estate capitalization rate					0.12						0.12		0.12
Cap rate | Minimum
Real Estate Properties [Line Items]
Real estate capitalization rate					0.06						0.06		0.06
Cap rate | Maximum
Real Estate Properties [Line Items]
Real estate capitalization rate					0.07						0.07		0.07
Real estate | SHOP | Assets Under Management Agreements
Real Estate Properties [Line Items]
Operating expenses | $											$ 35,000