Real Estate and Accumulated Depreciation (Schedule III Real Estate and Accumulated Depreciation) (Details) - USD ($) $ in Thousands		Dec. 31, 2016		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Real Estate and Accumulated Depreciation [Line Items]
Initial Cost of Encumbrances		$ 3,461,527
Initial Cost of Land		2,507,281
Initial Cost of Buildings & Improvements		25,667,979
Cost Capitalized Subsequent to Acquisition		2,049,147
Carrying Amount of Land		2,591,071
Carrying Amount of Buildings and Improvements		27,449,987
Accumulated Depreciation		4,093,494	[1]	$ 3,796,297	$ 3,020,908	$ 2,386,658
Investments In Real Property Owned Continuing Operations [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial Cost of Encumbrances		3,457,495
Initial Cost of Land		2,507,281
Initial Cost of Buildings & Improvements		25,667,979
Cost Capitalized Subsequent to Acquisition		2,049,147
Carrying Amount of Land		2,591,071
Carrying Amount of Buildings and Improvements		27,449,987
Accumulated Depreciation	[1]	4,093,494
Triple Net [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial Cost of Encumbrances		594,199
Initial Cost of Land		804,007
Initial Cost of Buildings & Improvements		7,794,067
Cost Capitalized Subsequent to Acquisition		718,637
Carrying Amount of Land		853,984
Carrying Amount of Buildings and Improvements		8,462,729
Accumulated Depreciation	[1]	1,317,149
Seniors Housing Operating [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial Cost of Encumbrances		2,400,836
Initial Cost of Land		1,085,554
Initial Cost of Buildings & Improvements		11,775,094
Cost Capitalized Subsequent to Acquisition		807,677
Carrying Amount of Land		1,151,566
Carrying Amount of Buildings and Improvements		12,516,758
Accumulated Depreciation	[1]	1,791,579
Outpatient Medical [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial Cost of Encumbrances		404,079
Initial Cost of Land		505,698
Initial Cost of Buildings & Improvements		4,548,662
Cost Capitalized Subsequent to Acquisition		450,707
Carrying Amount of Land		585,521
Carrying Amount of Buildings and Improvements		4,919,550
Accumulated Depreciation	[1]	984,766
Construction in Progress [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial Cost of Encumbrances		58,381
Initial Cost of Land		0
Initial Cost of Buildings & Improvements		506,091
Cost Capitalized Subsequent to Acquisition		0
Carrying Amount of Land		0
Carrying Amount of Buildings and Improvements		506,091
Accumulated Depreciation	[1]	0
Assets Held-for-sale [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial Cost of Encumbrances		4,032
Initial Cost of Land		112,022
Initial Cost of Buildings & Improvements		1,044,065
Cost Capitalized Subsequent to Acquisition		72,126
Carrying Amount of Land		0
Carrying Amount of Buildings and Improvements		1,044,859
Accumulated Depreciation	[1]	$ 0

[1] Please see Note 2 to our consolidated financial statements for information regarding lives used for depreciation and amortization.