Real Property Acquisitions and Development (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Estimated Fair Value of Allocated Purchase Price of Asset and Liabilities
Unsecured debt		$ (8,161,619)		$ (8,548,055)
Seniors Housing Operating [Member]
Estimated Fair Value of Allocated Purchase Price of Asset and Liabilities
Land and land improvements		164,653	[1]	218,581		$ 57,534
Buildings and improvements		1,518,472	[1]	2,367,486		297,314
Acquired lease intangibles		115,643	[1]	187,512		12,983
Construction in progress		0	[1]	0		27,957
Restricted cash		216	[1]	11,798		804
Receivables and other assets		2,462	[1]	29,501		9,327
Total assets acquired	[2]	1,801,446	[1]	2,814,878		405,919
Secured debt		(63,732)	[1]	(871,471)		(19,834)
Unsecured debt		0	[1]	(24,621)		0
Accrued expenses and other liabilities		(23,681)	[1]	(81,778)		(17,802)
Total liabilities assumed		(87,413)	[1]	(977,870)		(37,636)
Noncontrolling interests		(6,007)	[1]	(183,854)		(482)
Non-cash acquisition related activity	[3]	(47,065)	[1]	0		0
Cash disbursed for acquisitions		1,660,961	[1]	1,653,154		367,801
Construction in progress additions		157,845	[1]	44,173		12,291
Less: Capitalized interest		(5,793)	[1]	(1,740)		(714)
Foreign currency translation		(8,500)	[1]	(2,499)		(2,012)
Cash disbursed for construction in progress		143,552	[1]	39,934		9,565
Capital improvements to existing properties		138,673	[1]	104,308		86,803
Total cash invested in real property, net of cash acquired		1,943,186	[1]	1,797,396		464,169
Cash acquired from acquisition		135		30,930		9,060
Seniors Housing Operating [Member] | Preliminary [Member]
Estimated Fair Value of Allocated Purchase Price of Asset and Liabilities
Total cash invested in real property, net of cash acquired		1,672,961
Triple Net [Member]
Estimated Fair Value of Allocated Purchase Price of Asset and Liabilities
Land and land improvements		104,754	[4]	95,835		141,387
Buildings and improvements		418,633	[4]	1,061,431		1,365,638
Acquired lease intangibles		2,876	[4]	4,408		19,196
Restricted cash		0	[4]	6		0
Receivables and other assets		551	[4]	194		4,895
Total assets acquired	[5]	526,814	[4]	1,161,874		1,531,116
Secured debt		0	[4]	(47,741)		(130,638)
Unsecured debt		0	[4]	0		(48,567)
Accrued expenses and other liabilities		(3,384)	[4]	(2,905)		(9,067)
Total liabilities assumed		(3,384)	[4]	(50,646)		(188,272)
Noncontrolling interests		(26,771)	[4]	(13,465)		0
Non-cash acquisition related activity	[6]	(51,733)	[4]	(38,355)		(3,453)
Cash disbursed for acquisitions		444,926	[4]	1,059,408		1,339,391
Construction in progress additions		181,084	[4]	143,140		135,349
Less: Capitalized interest		(8,729)	[4]	(5,699)		(4,582)
Foreign currency translation		(3,665)	[4]	(167)		421
Non-cash related activity		0	[4]	0		14,459
Cash disbursed for construction in progress		168,690	[4]	137,274		116,729
Capital improvements to existing properties		32,603	[4]	45,293		18,901
Total cash invested in real property, net of cash acquired		646,219	[4]	1,241,975		1,475,021
Cash acquired from acquisition		682		16,572		1,382
Non Cash Acquisition Financed As Real Estate Loan Receivable		45,044		23,288
Non cash acquisition financed as equity investments		6,630		6,743
Triple Net [Member] | Senior Notes [Member]
Estimated Fair Value of Allocated Purchase Price of Asset and Liabilities
Unsecured debt		0		0		(48,567)
Triple Net [Member] | Preliminary [Member]
Estimated Fair Value of Allocated Purchase Price of Asset and Liabilities
Total cash invested in real property, net of cash acquired		67,847
Outpatient Medical [Member]
Estimated Fair Value of Allocated Purchase Price of Asset and Liabilities
Land and land improvements		5,738	[7]	223,708		63,129
Buildings and improvements		46,056	[7]	614,770		567,847
Acquired lease intangibles		4,592	[7]	45,226		46,661
Receivables and other assets		0	[7]	939		0
Total assets acquired	[8]	56,386	[7]	884,643		677,637
Secured debt		0	[7]	(120,977)		(66,113)
Accrued expenses and other liabilities		(1,670)	[7]	(7,777)		(22,293)
Total liabilities assumed		(1,670)	[7]	(128,754)		(88,406)
Noncontrolling interests		0	[7]	(76,535)		(39,987)
Non-cash acquisition related activity		(15,013)	[7],[9]	(27,025)	[10]	(45,836)	[9]
Cash disbursed for acquisitions		39,703	[7]	652,329		503,408
Construction in progress additions		113,933	[7]	70,560		99,878
Less: Capitalized interest		(3,723)	[7]	(1,286)		(1,854)
Accruals	[11]	(19,321)	[7]	(1,921)		(26,437)
Cash disbursed for construction in progress		90,889	[7]	67,353		71,587
Capital improvements to existing properties		47,870	[7]	38,151		27,076
Total cash invested in real property, net of cash acquired		178,462	[7]	757,833		602,071
Cash acquired from acquisition		0		$ 5,522		$ 0
Outpatient Medical [Member] | Preliminary [Member]
Estimated Fair Value of Allocated Purchase Price of Asset and Liabilities
Total cash invested in real property, net of cash acquired		$ 18,784

[1] Includes an aggregate purchase price of $1,672,961,000 relating to acquisitions for which the allocation of the purchase price consideration is preliminary and subject to change.

[2] Excludes $135,000, $30,930,000 and $9,060,000 of cash acquired during the years ended December 31, 2016, 2015 and 2014, respectively.

[3] Primarily relates to the acquisition of assets previously financed as an equity investment.

[4] Includes acquisitions with an aggregate purchase price of $67,847,000 for which the allocation of the purchase price consideration is preliminary and subject to change.

[5] Excludes $682,000, $16,572,000 and $1,382,000 of cash acquired during the year ended December 31, 2016, 2015 and 2014, respectively.

[6] For the year ended December 31, 2016, primarily relates to $45,044,000 for the acquisition of assets previously financed as real estate loans receivable and $6,630,000 previously financed as an equity investment. For the year ended December 31, 2015, primarily relates to $23,288,000 for the aquisition of assets previously financed as real estate loans receivable and $6,743,000 previously financed as equity investments.

[7] Includes acquisitions with an aggregate purchase price of $18,784,000 for which the allocation of the purchase price consideration is preliminary and subject to change.

[8] Excludes $0, $5,522,000 and $0 of cash acquired during the years ended December 31, 2016, 2015 and 2014, respectively.

[9] The non-cash activity relates to the acquisition of assets previously financed as real estate loans. Please refer to Note 6 for additional information.

[10] The non-cash activity relates to the acquisition of a controlling interest in a portfolio of properties that was historically reported as an unconsolidated property investment.

[11] Represents non-cash consideration accruals for amounts to be paid in future periods relating to properties that converted in the periods noted above.