Real Estate and Loans Receivable - 2016 Activity - Additional Information (Detail) $ in Thousands, € in Millions						1 Months Ended	12 Months Ended
		Oct. 21, 2016 USD ($) RenewalOptions Hospital	Oct. 03, 2016 USD ($) Facility RenewalOptions Hospital	Jul. 22, 2016 USD ($)	May 02, 2016 USD ($)	Sep. 30, 2015 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($) Hospital	Dec. 31, 2016 EUR (€) Hospital	Dec. 31, 2015 USD ($)	Jun. 22, 2016 EUR (€)
Business Acquisition [Line Items]
Loans repaid	[1]							$ 193,262		$ 385,851
Mortgage financing							$ 717,928	612,836		380,000
Mortgage financing funded								310,000		20,000
Median [Member]
Business Acquisition [Line Items]
Loans repaid										$ 385,900
Capella [Member]
Business Acquisition [Line Items]
Loans repaid								$ 93,300
2016 [Member] | General Acute Care Hospital and Healthcare System [Member]
Business Acquisition [Line Items]
Term of lease, years		15 years
Number of lease extension options | RenewalOptions		3
Number of facilities acquired | Hospital		3
Lease agreement, end date		2031-05
Number of free-standing emergency department and health center | Hospital		1
Mortgage financing						$ 100,000
Mortgage financing funded		$ 15,000
2016 [Member] | Rehabilitation Hospital with Covenant Health System [Member] | Germany [Member]
Business Acquisition [Line Items]
Number of facilities acquired | Hospital								12	12
Acquisition costs | €									€ 85.2
2016 [Member] | Rehabilitation Hospital with Covenant Health System [Member] | Germany [Member] | 2015 Master Lease [Member]
Business Acquisition [Line Items]
Number of facilities acquired | Hospital								5	5
Acquisition costs | €									€ 35.7
2016 [Member] | Rehabilitation Hospital with Covenant Health System [Member] | Germany [Member] | Third Master Lease [Member]
Business Acquisition [Line Items]
Number of facilities acquired | Hospital								7	7
Acquisition costs | €									€ 49.5
Lease agreement, end date								2043-08	2043-08
Term of lease								27 years	27 years
2016 [Member] | Median [Member]
Business Acquisition [Line Items]
Value of properties closed | €											€ 41.6
2016 [Member] | Steward [Member]
Business Acquisition [Line Items]
Number of hospitals closed | Hospital			9
Combined purchase price and investment amount			$ 1,250,000
Number of licensed hospitals | Hospital			5
Cash paid for acquisition transaction			$ 600,000
Loans repaid			600,000
Equity interest acquired			$ 50,000
Term of lease, years			15 years
Number of lease extension options | RenewalOptions			3
Number of facilities for making mortgage loans | Facility			4
Lease expiration date			Oct. 31, 2031
2016 [Member] | Capella [Member] | Olympia, Washington [Member]
Business Acquisition [Line Items]
Cash paid for acquisition transaction				$ 7,000
Loans repaid				$ 93,300
2016 [Member] | Acute Care Hospital [Member] | New Jersey [Member]
Business Acquisition [Line Items]
Acquisition costs					$ 63,000
Commitment to advance an additional amount for capital additions					$ 30,000
Commitment period to advance an additional amount for capital additions					3 years
2016 [Member] | Business Acquisitions [Member]
Business Acquisition [Line Items]
Revenue contributed by the acquired entity								$ 37,400
Income contributed by the acquired entity								31,700
Acquisition related costs								$ 12,100

[1] The 2016 column includes $93.3 million of loans advanced to Capella in 2015 and repaid in 2016 as a part of the Capella transaction, along with $100.0 million loans advanced to Prime in 2015 and repaid in 2016 as part of the sale leaseback conversion of four properties in New Jersey. The 2015 column includes $385.9 million of loans advanced to MEDIAN in 2014 and repaid in 2015 as a part of the MEDIAN transaction.