Subsequent Event - Additional Information (Detail) shares in Thousands, £ in Millions					6 Months Ended
	Jul. 26, 2019 USD ($)	Jul. 23, 2019 GBP (£) Hospital	Jul. 18, 2019 USD ($) shares	Jul. 10, 2019 USD ($) Hospital RenewalOption Lease Health_Center	Jun. 30, 2019 USD ($) shares	Dec. 31, 2018 USD ($) shares
Subsequent Event [Line Items]
Mortgage loan balance					$ 1,587,073,000	$ 1,586,520,000
Common stock, shares issued | shares					394,425	370,637
Proceeds from sale of common shares, net of offering costs					$ 399,353,000
Maximum [Member]
Subsequent Event [Line Items]
Term of lease					15 years
Minimum [Member]
Subsequent Event [Line Items]
Term of lease					10 years
Mortgage Loans [Member]
Subsequent Event [Line Items]
Mortgage loan balance					$ 1,216,442,000	$ 1,213,322,000
Subsequent Event [Member]
Subsequent Event [Line Items]
Purchase price of acquisition				$ 1,400,000,000
Number of master leases | Lease				2
Term loan				$ 112,900,000
Additional number of businesses acquired | Hospital				2
Subsequent Event [Member] | 4.625% Senior Unsecured Notes Due 2029 [Member]
Subsequent Event [Line Items]
Senior unsecured notes face amount	$ 900,000,000
Senior unsecured notes, interest rate	4.625%
Senior unsecured notes, payable term	Interest on the notes is payable semi-annually on February 1 and August 1 of each year, commencing on February 1, 2020.
Percentage of par value on senior notes	99.50%
Senior unsecured notes, maturity date	Aug. 01, 2029
Senior notes, earliest redemption date	Aug. 01, 2024
Senior unsecured notes, redemption description	We may redeem some or all of the notes at any time prior to August 1, 2024 at a “make whole” redemption price. On or after August 1, 2024, we may redeem some or all of the notes at a premium that will decrease over time. In addition, at any time prior to August 1, 2022, we may redeem up to 40% of the notes at a redemption price equal to 104.625% of the aggregate principal amount thereof, plus accrued and unpaid interest thereon, using proceeds from one or more equity offerings. In the event of a change in control, each holder of the notes may require us to repurchase some or all of the notes at a repurchase price equal to 101% of the aggregate principal amount of the notes plus accrued and unpaid interest to the date of purchase.
Debt instrument, redemption price percentage	104.625%
Senior notes, repurchased price percentage on principal amount plus accrued and unpaid interest	101.00%
Subsequent Event [Member] | Senior Unsecured Term Loan Facility [Member] | Barclays Bank PLC [Member]
Subsequent Event [Line Items]
Cancellation of loan	$ 1,550,000,000
Underwriting and other fees	$ 3,900,000
Subsequent Event [Member] | Maximum [Member] | 4.625% Senior Unsecured Notes Due 2029 [Member]
Subsequent Event [Line Items]
Senior unsecured notes, redemption percentage on principal amount	40.00%
Subsequent Event [Member] | Public Offering [Member]
Subsequent Event [Line Items]
Common stock, shares issued | shares			51,750
Additional shares purchased by underwriters | shares			6,750
Proceeds from sale of common shares, net of offering costs			$ 858,100,000
Subsequent Event [Member] | Acute Care Hospital [Member]
Subsequent Event [Line Items]
Number of facilities acquired | Hospital				11
Subsequent Event [Member] | Acute Care Hospital [Member] | Mortgage Loans [Member]
Subsequent Event [Line Items]
Mortgage loan balance				$ 51,300,000
Subsequent Event [Member] | Behavioral Health Care Facility [Member]
Subsequent Event [Line Items]
Number of facilities acquired | Health_Center				2
Subsequent Event [Member] | Secure Income REIT [Member]
Subsequent Event [Line Items]
Purchase price of acquisition | £		£ 347
Subsequent Event [Member] | Prospect Medical Holdings Inc [Member]
Subsequent Event [Line Items]
Purchase price of acquisition				$ 1,550,000,000
Term of lease				15 years
Number of lease extension options | RenewalOption				3
Subsequent Event [Member] | Prospect Medical Holdings Inc [Member] | Acute Care Hospital [Member]
Subsequent Event [Line Items]
Number of facilities acquired | Hospital				14
Subsequent Event [Member] | Prospect Medical Holdings Inc [Member] | Behavioral Health Care Facility [Member]
Subsequent Event [Line Items]
Number of facilities acquired | Health_Center				2
Subsequent Event [Member] | England [Member] | Secure Income REIT [Member]
Subsequent Event [Line Items]
Number of private hospitals acquired | Hospital		8
Subsequent Event [Member] | Ramsay Health Care [Member]
Subsequent Event [Line Items]
Term of lease		18 years