Subsequent Events (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Apr. 01, 2018 USD ($) Number $ / shares	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Subsequent Event [Line Items]
Senior unsecured notes		$ 7,924,340	$ 8,331,722
Investment in joint venture		$ 440,424	$ 445,585
Maturity Date		May 13, 2021
Subsequent Event [Member] | Barclays [Member]
Subsequent Event [Line Items]
Commitment To Unsecured Credit Facility Maximum Borrowing Capacity	$ 1,000,000
Subsequent Event [Member] | ProMedica Member [Member]
Subsequent Event [Line Items]
Joint venture ownership	20.00%
Lessor, Operating Lease, Lease Not yet Commenced, Description	(i) 15-year absolute triple-net master lease with three five-year renewal options; (ii) 8% initial cash rental yield with a year one escalator of 1.375% and 2.75% annual escalator thereafter; and (iii) full corporate guarantee of ProMedica
Lessor, Operating Lease, Lease Not yet Commenced, Term of Contract	15 years
Lessor, Operating Lease, Lease Not yet Commenced, Existence of Option to Extend [true/false]	true
Lease Agreement Number Of Renewal Options | Number	3
Lessor, Operating Lease, Lease Not yet Commenced, Renewal Term	5 years
Lease Agreement Initial Cash Rental Yield	8.00%
Lease Agreement Escalator In Year One	1.375%
Lease Agreement Annual Escalator Thereafter	2.75%
Subsequent Event [Member] | Joint Venture With ProMedica [Member]
Subsequent Event [Line Items]
Joint venture ownership	80.00%
Subsequent Event [Member] | Joint Venture With ProMedica [Member] | ProMedica Member [Member]
Subsequent Event [Line Items]
Joint venture ownership	20.00%
Subsequent Event [Member] | Joint Venture With ProMedica [Member] | Scenario, Forecast [Member]
Subsequent Event [Line Items]
Investment in joint venture	$ 2,200,000
Subsequent Event [Member] | Quality Care Properties Inc [Member]
Subsequent Event [Line Items]
Purchase price per share | $ / shares	$ 20.75
Equity Method Investment, Description of Principal Activities	own the real estate of QCP’s principal tenants, HCR ManorCare and Arden Courts
Subsequent Event [Member] | 4.25% Senior Unsecured Notes Due 2028
Subsequent Event [Line Items]
Interest rate	4.25%
Senior unsecured notes issued amount	$ 550,000
Debt issuance proceeds	$ 545,199
Maturity Date	Dec. 31, 2028