Disclosure about Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2016		Dec. 31, 2015	Mar. 31, 2015		Dec. 31, 2014
Financial Assets:
Loans receivable, Fair value	$ 572,909		$ 663,501
Available-for-sale equity investments, Carrying Amount	15,230		22,779
Available-for-sale equity investments, Fair Value	15,230	[1]	22,779
Cash and cash equivalents, Carrying Amount	355,949		360,908	$ 202,273		$ 473,726
Cash and cash equivalents, Fair Value	355,949		360,908
Foreign Currency Forward Contracts Carrying Value	100,162		129,520
Foreign Currency Forward Contracts Fair Value	100,162		129,520
Financial Liabilities:
Borrowings under primary unsecured credit facilities, Carrying Value	645,000	[2]	835,000	$ 410,000	[2]
Borrowings under primary unsecured credit facilities, Fair Value	645,000		835,000
Senior unsecured notes, Carrying Amount	8,828,053		8,548,055
Senior unsecured notes, Fair Value	9,391,062		9,020,529
Secured debt, Carrying Amount	3,515,053		3,509,142
Secured debt, Fair Value	3,724,054		3,678,564
Foreign Currency Forward Contracts Carrying Value	2,308		0
Foreign Currency Forward Contracts, Fair Value	2,308		0
Redeemable OP unitholder interests carrying value	114,481		112,029
Redeemable OP unitholder interests fair value	114,481		112,029
Mortgage Loans on Real Estate [Member]
Financial Assets:
Loans receivable, Carrying Amount	546,573		635,492
Loans receivable, Fair value	572,909		663,501
Other Real Estate Loans Receivable [Member]
Financial Assets:
Loans receivable, Carrying Amount	178,718		184,000
Loans receivable, Fair value	$ 182,829		$ 185,693

[1] (1) Unrealized gains or losses on equity investments are recorded in accumulated other comprehensive income (loss) at each measurement date. During the year ended December 31, 2015, we recognized an other than temporary impairment charge of $35,648,000 on the Genesis Healthcare stock investment. Also, see Note 11 for details related to the gain on the derivative asset originally recognized.

[2] (1) As of March 31, 2016, letters of credit in the aggregate amount of $48,930,000 have been issued, which reduces the borrowing capacity on the unsecured revolving credit facility.