Real Estate and Lending Activities - Schedule of Gross Assets by Operator (Detail) - USD ($) $ in Thousands		9 Months Ended	12 Months Ended
		Sep. 30, 2017	Dec. 31, 2016
Investment And Revenue From External Customers [Line Items]
Total Gross Assets		$ 8,927,040	$ 6,418,536
Total Gross Assets [Member] | Credit Concentration Risk [Member]
Investment And Revenue From External Customers [Line Items]
Total Gross Assets		$ 9,355,935	$ 7,143,121
Percentage of Total Gross Assets		100.00%	100.00%
Total Gross Assets [Member] | Credit Concentration Risk [Member] | Steward [Member]
Investment And Revenue From External Customers [Line Items]
Total Gross Assets	[1]	$ 3,445,379	$ 1,609,583
Percentage of Total Gross Assets	[1]	36.80%	22.50%
Total Gross Assets [Member] | Credit Concentration Risk [Member] | MEDIAN [Member]
Investment And Revenue From External Customers [Line Items]
Total Gross Assets		$ 1,209,767	$ 993,677
Percentage of Total Gross Assets		12.90%	13.90%
Total Gross Assets [Member] | Credit Concentration Risk [Member] | Prime [Member]
Investment And Revenue From External Customers [Line Items]
Total Gross Assets		$ 1,118,070	$ 1,144,055
Percentage of Total Gross Assets		12.00%	16.00%
Total Gross Assets [Member] | Credit Concentration Risk [Member] | Ernest [Member]
Investment And Revenue From External Customers [Line Items]
Total Gross Assets		$ 631,501	$ 627,906
Percentage of Total Gross Assets		6.70%	8.80%
Total Gross Assets [Member] | Credit Concentration Risk [Member] | RCCH [Member]
Investment And Revenue From External Customers [Line Items]
Total Gross Assets		$ 506,265	$ 566,600
Percentage of Total Gross Assets		5.40%	7.90%
Total Gross Assets [Member] | Credit Concentration Risk [Member] | Other Operators [Member]
Investment And Revenue From External Customers [Line Items]
Total Gross Assets		$ 1,992,448	$ 1,900,397
Percentage of Total Gross Assets		21.30%	26.70%
Total Gross Assets [Member] | Credit Concentration Risk [Member] | Other Assets [Member]
Investment And Revenue From External Customers [Line Items]
Total Gross Assets		$ 452,505	$ 300,903
Percentage of Total Gross Assets		4.90%	4.20%

[1] (1) Includes approximately $360 million of gross assets as of December 31, 2016 related to facilities leased to IASIS prior to it being acquired by Steward on September 29, 2017.