Dispositions (Real Estate Assets Held for Sale) (Details) $ in Thousands	Dec. 31, 2015 USD ($) property	Dec. 31, 2014 USD ($) property
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Properties Held for Sale | property	11	365
Assets Held for Sale	$ 93,060	$ 2,555,322
Liabilities Held for Sale	$ 34,340	$ 237,973
Triple-net leased properties
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Properties Held for Sale | property	2	333
Assets Held for Sale	$ 4,488	$ 2,410,840
Liabilities Held for Sale	$ 44	$ 205,931
MOB operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Properties Held for Sale | property	8	32
Assets Held for Sale	$ 68,619	$ 144,482
Liabilities Held for Sale	$ 24,759	$ 32,042
Seniors living operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Properties Held for Sale | property	1	0
Assets Held for Sale	$ 19,953	$ 0
Liabilities Held for Sale	$ 9,537	$ 0