Acquisitions and Dispositions - (Details) $ in Thousands		3 Months Ended								12 Months Ended
	Mar. 01, 2018 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) properties states land	Dec. 31, 2017 USD ($) parking_deck condominium_units properties states	Dec. 31, 2016 USD ($)
Business Acquisition [Line Items]
Number of operating healthcare properties | properties											40
Number of states in which operating healthcare properties and land parcel located | states											15
Net income (loss) attributable to redeemable noncontrolling interest	$ 6,400
Acquisition price										$ 271,000	$ 1,414,179
Revenue of acquiree since acquisition date		$ 105,311	$ 105,028	$ 106,989	$ 105,223	$ 97,320	$ 92,999	$ 76,599	$ 76,666	422,551	343,584	$ 241,034
Net income (loss)		$ 11,156	$ 23,771	$ 12,062	$ 11,332	$ 10,187	$ 12,539	$ 10,331	$ 6,716	58,321	$ 39,773	$ 31,522
Number of condominium units | condominium_units											2
Number of parking decks | parking_deck											1
Loan Investments
Business Acquisition [Line Items]
Asset acquisition, consideration transferred										11,800
Acquisition price										$ 11,750
Four Healthcare Properties Acquired In 2018
Business Acquisition [Line Items]
Number of operating healthcare properties | properties										4
Number of land parcels | land										1
Number of states in which operating healthcare properties and land parcel located | states										5
Asset acquisition, consideration transferred										$ 252,800
Noncontrolling Interest Buyout
Business Acquisition [Line Items]
Asset acquisition, consideration transferred										271,000
Net income (loss) attributable to redeemable noncontrolling interest										$ 6,400
Conversion And Satisfaction Of Previously Outstanding Construction Loan
Business Acquisition [Line Items]
Number of operating healthcare properties | properties										2
Asset acquisition, consideration transferred										$ 18,800
Total Asset Acquisitions
Business Acquisition [Line Items]
Revenue of acquiree since acquisition date										14,700	$ 49,600
Net income (loss)										$ 5,400	8,600
Forty Health Care Properties Acquired in 2017
Business Acquisition [Line Items]
Acquisition price											1,370,000
Lease Structuring Arrangement And Equity Recapitalization [Member]
Business Acquisition [Line Items]
Number of land parcels | land										2
Noncontrolling Interest Buyout
Business Acquisition [Line Items]
Acquisition price											1,410,000
Equity Buyout - Foundation
Business Acquisition [Line Items]
Acquisition price											2,800
Redeemable Noncontrolling Interest Buyouts
Business Acquisition [Line Items]
Net income (loss) attributable to redeemable noncontrolling interest											1,100
Loan Investments
Business Acquisition [Line Items]
Acquisition price											$ 39,063