Loans Receivable - Other Secured Loans (Details) $ in Thousands	1 Months Ended							3 Months Ended	12 Months Ended
	Dec. 31, 2015 GBP (£)	Sep. 30, 2015 GBP (£) property	Apr. 30, 2015 GBP (£) property	Feb. 28, 2015 GBP (£)	Feb. 28, 2015 USD ($)	Nov. 30, 2014 GBP (£) property item	Nov. 30, 2014 USD ($) property item	Mar. 31, 2016 USD ($) property	Dec. 31, 2015 GBP (£)	Dec. 31, 2015 USD ($)	Dec. 31, 2015 USD ($)	May. 31, 2015 USD ($)	Feb. 28, 2015 USD ($)	Jun. 30, 2013 USD ($)	Jul. 31, 2012 USD ($)	Jun. 30, 2012 GBP (£)
Loans Receivable:
Loans receivable, other								$ 116,818			$ 114,322
Amount draw on the revolving line of credit facility								422,897
Loan amount outstanding								$ 810,313			397,432
NHP[Member]
Loans Receivable:
Number of facilities | property						273	273
Number of beds acquired | item						12,500	12,500
HC-One Facility
Loans Receivable:
Number of facilities | property			36
Loan facility maximum				£ 502,000,000		£ 395,000,000							$ 795,000
Amount draw on the revolving line of credit facility						£ 363,000,000	$ 574,000
Term of facility						5 years	5 years
Increase in loan facility		£ 11,000,000		£ 108,000,000	$ 164,000
Amount of facility converted into sale-leaseback transaction | £			£ 174,000,000
Paydowns received | £		£ 34,000,000
Non-call period shortened		17 months
Number of properties spinoff into a separate joint venture | property		36						36
Term to retain security over the spinoff properties		2 years
Cash payments received from borrower									£ 34,000,000	$ 52,000
Loan amount outstanding								$ 395,000
Tandem Health Care Loan
Loans Receivable:
Loan facility maximum															$ 205,000
Loans receivable, other								$ 256,000
Loan receivable, interest rate payable (as a percent)								11.50%
Loan receivable subordinated to senior mortgage debt								$ 380,000
Tandem Health Care Loan - First Tranche
Loans Receivable:
Loans receivable, other															$ 100,000
Loan receivable, interest rate payable (as a percent)								12.00%
Tandem Health Care Loan - Second Tranche
Loans Receivable:
Loans receivable, other														$ 102,000
Loan receivable, interest rate payable (as a percent)								14.00%
Tandem Health Care Loan Third Tranche [Member]
Loans Receivable:
Loans receivable, other												$ 50,000
Loan receivable, interest rate payable (as a percent)								6.00%
Tandem Health Care Loan Fourth Tranche [Member]
Loans Receivable:
Loans receivable, other												$ 5,000
Loan receivable, interest rate payable (as a percent)								6.00%
Four Seasons
Loans Receivable:
Marketable debt security, par value	£ 28,000,000								28,000,000		$ 42,000					£ 138,500,000
Marketable debt security, issued and outstanding | £	£ 40,000,000								£ 40,000,000
Four Seasons | LIBOR
Loans Receivable:
Loan, basis spread on variable rate	6.00%