Investments in Unconsolidated Ventures - Summary of Unconsolidated Ventures (Details) $ in Thousands	1 Months Ended	6 Months Ended
	Dec. 31, 2015 USD ($)	Jun. 30, 2019 USD ($) facility	Jun. 30, 2018 USD ($)	Nov. 01, 2018	Oct. 31, 2018	Jul. 31, 2017 USD ($)	Jul. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	May 31, 2014 USD ($)
Investments [Abstract]
Purchase price | $		$ 6,319,162
Equity investment | $		$ 511,124
Total		558
Payments to acquire interest in joint venture | $		$ 39,801	$ 4,470
Senior Housing Facilities
Investments [Abstract]
Total		151
MOB
Investments [Abstract]
Total		108
SNF
Investments [Abstract]
Total		290
Hospitals
Investments [Abstract]
Total		9
Eclipse
Investments [Abstract]
Ownership interest (as a percentage)		5.60%
Purchase price | $									$ 1,048,000
Equity investment | $		$ 23,400
Properties		76
Eclipse | Senior Housing Facilities
Investments [Abstract]
Properties		44
Eclipse | MOB
Investments [Abstract]
Properties		0
Eclipse | SNF
Investments [Abstract]
Properties		32
Eclipse | Hospitals
Investments [Abstract]
Properties		0
Griffin-American
Investments [Abstract]
Ownership interest (as a percentage)		14.30%
Purchase price | $								$ 3,238,547
Equity investment | $		$ 243,544
Properties		250
Payments to acquire interest in joint venture | $		$ 37,400
Griffin-American | Senior Housing Facilities
Investments [Abstract]
Properties		92
Griffin-American | MOB
Investments [Abstract]
Properties		108
Griffin-American | SNF
Investments [Abstract]
Properties		41
Griffin-American | Hospitals
Investments [Abstract]
Properties		9
Espresso
Investments [Abstract]
Ownership interest (as a percentage)		36.70%
Purchase price | $							$ 870,000
Equity investment | $		$ 55,146
Properties		155
Espresso | Senior Housing Facilities
Investments [Abstract]
Properties		6
Espresso | MOB
Investments [Abstract]
Properties		0
Espresso | SNF
Investments [Abstract]
Properties		149
Espresso | Hospitals
Investments [Abstract]
Properties		0
Trilogy
Investments [Abstract]
Ownership interest (as a percentage)	29.00%	23.20%		23.00%	29.00%
Purchase price | $	$ 1,162,613
Equity investment | $		$ 189,032
Properties		77
Payments to acquire interest in joint venture | $	$ 201,700	$ 2,400
Ownership interest sold (as a percentage)					20.00%
Trilogy | Senior Housing Facilities
Investments [Abstract]
Properties		9
Trilogy | MOB
Investments [Abstract]
Properties		0
Trilogy | SNF
Investments [Abstract]
Properties		68
Trilogy | Hospitals
Investments [Abstract]
Properties		0
Eclipse, Griffin-American, Espresso, Trilogy
Investments [Abstract]
Purchase price | $		$ 6,319,160
Equity investment | $		$ 511,122
Properties		558
Eclipse, Griffin-American, Espresso, Trilogy | Senior Housing Facilities
Investments [Abstract]
Properties		151
Eclipse, Griffin-American, Espresso, Trilogy | MOB
Investments [Abstract]
Properties		108
Eclipse, Griffin-American, Espresso, Trilogy | SNF
Investments [Abstract]
Properties		290
Eclipse, Griffin-American, Espresso, Trilogy | Hospitals
Investments [Abstract]
Properties		9
Operator Platform
Investments [Abstract]
Ownership interest (as a percentage)		20.00%
Purchase price | $						$ 2
Equity investment | $		$ 2
Properties		0
Operator Platform | Senior Housing Facilities
Investments [Abstract]
Properties		0
Operator Platform | MOB
Investments [Abstract]
Properties		0
Operator Platform | SNF
Investments [Abstract]
Properties		0
Operator Platform | Hospitals
Investments [Abstract]
Properties		0
Winterfell
Investments [Abstract]
Ownership interest (as a percentage)		20.00%
Winterfell | Solstice Senior Living
Investments [Abstract]
Ownership interest (as a percentage)		80.00%