Other Assets (Details) $ in Thousands	1 Months Ended
	Sep. 30, 2015 USD ($) item	Jun. 30, 2012 GBP (£)	Jun. 30, 2012 USD ($)	Dec. 31, 2014 USD ($)
Other assets
Straight-line rent receivables, net of allowance of $33,527 and $34,182, respectively	$ 378,295			$ 355,864
Allowance on straight-line rent assets	33,527			34,182
Marketable debt securities	118,019			231,442
Leasing costs, net	158,297			146,500
Deferred financing costs, net	53,750			47,592
Goodwill	50,346			50,346
Other	124,626			108,428
Total other assets	883,333			940,172
Loans receivables	765,593			906,961
Four Seasons Health Care Ltd [Member]
Other assets
Total amount outstanding | £		£ 175,000,000
Brookdale Senior Living
Other assets
Loans receivables	$ 14,000			26,000
Number of installments | item	8
Four Seasons
Other assets
Investment Interest Rate	12.25%
Marketable debt security, par value | £		138,500,000
Purchase of debt securities		£ 136,800,000	$ 215,000
Portion of debt held, as a percent.		79.00%	79.00%
HCP Ventures IV
Other assets
Loans receivables	$ 21,000			$ 15,000
Loan receivable, interest rate payable (as a percent)	12.00%