Real Estate and Lending Activities - Schedule of Gross Assets by Operator (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Investment And Revenue From External Customers [Line Items]
Total Gross Assets	$ 5,710,395		$ 5,609,351
Assets, Total [Member] | Credit Concentration Risk [Member]
Investment And Revenue From External Customers [Line Items]
Total Gross Assets	$ 5,662,830	$ 6,035,922
Percentage of Total Gross Assets	100.00%	100.00%
Assets, Total [Member] | Credit Concentration Risk [Member] | Prime [Member]
Investment And Revenue From External Customers [Line Items]
Total Gross Assets	$ 1,125,994	$ 1,032,353
Percentage of Total Gross Assets	19.90%	17.10%
Assets, Total [Member] | Credit Concentration Risk [Member] | Median [Member]
Investment And Revenue From External Customers [Line Items]
Total Gross Assets	$ 1,080,381	$ 1,031,039
Percentage of Total Gross Assets	19.10%	17.10%
Assets, Total [Member] | Credit Concentration Risk [Member] | Ernest [Member]
Investment And Revenue From External Customers [Line Items]
Total Gross Assets	$ 581,087	$ 579,182
Percentage of Total Gross Assets	10.30%	9.60%
Assets, Total [Member] | Credit Concentration Risk [Member] | Capella [Member]
Investment And Revenue From External Customers [Line Items]
Total Gross Assets	$ 510,895	$ 1,059,989
Percentage of Total Gross Assets	9.00%	17.60%
Assets, Total [Member] | Credit Concentration Risk [Member] | Adeptus Health [Member]
Investment And Revenue From External Customers [Line Items]
Total Gross Assets	$ 500,000	$ 500,000
Percentage of Total Gross Assets	8.80%	8.30%