Real Estate and Loans Receivable - Schedule of Investment and Revenue by Operator (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Investment And Revenue From External Customers [Line Items]
Total Assets	$ 5,609,351				$ 3,720,330				$ 5,609,351	$ 3,720,330
Revenue	131,546	$ 114,570	$ 99,801	$ 95,961	82,106	$ 80,777	$ 76,560	$ 73,089	441,878	312,532	$ 242,523
Assets, Total [Member] | Credit Concentration Risk [Member] | Prime [Member]
Investment And Revenue From External Customers [Line Items]
Total Assets	1,032,353				749,553				$ 1,032,353	$ 749,553
Assets									18.40%	20.10%
Assets, Total [Member] | Credit Concentration Risk [Member] | Capella [Member]
Investment And Revenue From External Customers [Line Items]
Total Assets	1,015,914								$ 1,015,914
Assets									18.10%
Assets, Total [Member] | Credit Concentration Risk [Member] | Median [Member]
Investment And Revenue From External Customers [Line Items]
Total Assets	978,529				707,437				$ 978,529	$ 707,437
Assets									17.40%	19.00%
Assets, Total [Member] | Credit Concentration Risk [Member] | Ernest [Member]
Investment And Revenue From External Customers [Line Items]
Total Assets	$ 569,375				$ 486,758				$ 569,375	$ 486,758
Assets									10.20%	13.10%
Revenue [Member] | Credit Concentration Risk [Member] | Prime [Member]
Investment And Revenue From External Customers [Line Items]
Revenue									$ 104,325	$ 84,038
Assets									23.60%	26.90%
Revenue [Member] | Credit Concentration Risk [Member] | Capella [Member]
Investment And Revenue From External Customers [Line Items]
Revenue									$ 28,567
Assets									6.40%
Revenue [Member] | Credit Concentration Risk [Member] | Median [Member]
Investment And Revenue From External Customers [Line Items]
Revenue									$ 78,540	$ 23,663
Assets									17.80%	7.60%
Revenue [Member] | Credit Concentration Risk [Member] | Ernest [Member]
Investment And Revenue From External Customers [Line Items]
Revenue									$ 61,988	$ 57,315
Assets									14.00%	18.30%