Impairments (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2018 USD ($) property	Dec. 31, 2018 USD ($) property	Dec. 31, 2017 USD ($) property	Dec. 31, 2016 USD ($) property
Impaired Long-Lived Assets Held and Used [Line Items]
Impairments (recoveries), net		$ 55,260	$ 166,384	$ 0
Casualty-Related
Casualty-related loss			13,000
Property damage loss in a casualty			8,000
Other associated costs with casualty loss			5,000
Deferred tax benefit related to casualty loss			$ 1,000
SHOP
Impaired Long-Lived Assets Held and Used [Line Items]
Number of real estate properties impaired (in properties) | property	4	17
Impairments (recoveries), net	$ 33,000	$ 52,000
SHOP | Underperformed assets
Impaired Long-Lived Assets Held and Used [Line Items]
Number of real estate properties impaired (in properties) | property		3
Senior housing triple-net
Impaired Long-Lived Assets Held and Used [Line Items]
Number of real estate properties impaired (in properties) | property			11
Number of properties classified as held for sale (in properties) | property			64	64
Impairments (recoveries), net			$ 23,000
Other nonoperating income (expense)
Casualty-Related
Casualty-related loss			12,000
Equity income (loss) from unconsolidated joint ventures
Casualty-Related
Casualty-related loss			$ 1,000
Held-for-sale | Life science
Impaired Long-Lived Assets Held and Used [Line Items]
Number of properties classified as held for sale (in properties) | property			4
Held-for-sale | SHOP
Impaired Long-Lived Assets Held and Used [Line Items]
Number of properties classified as held for sale (in properties) | property	9	9	6
Held-for-sale | Senior housing triple-net
Impaired Long-Lived Assets Held and Used [Line Items]
Number of properties classified as held for sale (in properties) | property			2
Land | Held-for-sale | Life science
Impaired Long-Lived Assets Held and Used [Line Items]
Number of properties classified as held for sale (in properties) | property	1	1