Real Property Acquisitions and Development (Details) (USD $)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Seniors Housing Operating [Member]
Estimated Fair Value of Allocated Purchase Price of Asset and Liabilities
Land and land improvements	$ 445,152,000	[1]	$ 146,332,000		$ 112,350,000
Buildings and improvements	4,275,046,000	[1]	1,341,560,000		1,512,764,000
Acquired lease intangibles	396,444,000	[1]	118,077,000		122,371,000
Restricted cash	44,427,000	[1]	1,296,000		20,699,000
Receivables and other assets	79,564,000	[1]	10,125,000		901,000
Total assets acquired	5,240,633,000	[1],[2]	1,617,390,000	[2]	1,769,085,000	[2]
Secured debt	(1,275,245,000)	[1]	(124,190,000)		(796,272,000)
Accrued expenses and other liabilities	(96,709,000)	[1]	(17,347,000)		(44,483,000)
Total liabilities assumed	(1,371,954,000)	[1]	(141,537,000)		(840,755,000)
Capital in excess of par	0	[1]	0		(6,017,000)
Noncontrolling interests	(232,575,000)	[1]	(56,884,000)		(69,984,000)
Non-cash acquisition related activity	(555,563,000)	[2],[3]	0	[3]	0	[3]
Cash disbursed for acquisitions	3,080,541,000	[1]	1,418,969,000		852,329,000
Construction in progress additions	3,894,000		0		0
Less: Capitalized interest	(57,000)	[1]	0		0
Cash disbursed for construction in progress	3,837,000	[1]	0		0
Capital improvements to existing properties	72,258,000	[1]	21,751,000		15,880,000
Total cash invested in real property	3,156,636,000	[1]	1,440,720,000		868,209,000
Cash acquired from acquisition	92,148,000		20,691,000		38,952,000
Seniors Housing Operating [Member] | Preliminary [Member]
Estimated Fair Value of Allocated Purchase Price of Asset and Liabilities
Total cash invested in real property	1,318,168,000
Senior Housing Facilities Triple Net [Member]
Estimated Fair Value of Allocated Purchase Price of Asset and Liabilities
Land and land improvements	54,596,000	[4]	87,242,000		212,156,000
Buildings and improvements	265,390,000	[4]	984,077,000		3,108,508,000
Restricted cash	189,000	[4]	0		0
Receivables and other assets	1,020,000	[4]	119,000		9,101,000
Total assets acquired	321,195,000	[4],[5]	1,071,438,000	[5]	3,329,765,000	[5]
Secured debt	(9,810,000)	[4]	(89,881,000)		(93,431,000)
Accrued expenses and other liabilities	(540,000)	[4]	(3,542,000)		(91,290,000)
Total liabilities assumed	(10,350,000)	[4]	(93,423,000)		(184,721,000)
Capital in excess of par	0	[4]	921,000		0
Noncontrolling interests	0	[4]	(17,215,000)		0
Non-cash acquisition related activity	(151,000)	[4]	(616,000)		(2,532,000)
Cash disbursed for acquisitions	310,694,000	[4]	961,105,000		3,142,512,000
Construction in progress additions	141,129,000	[4]	179,684,000		182,626,000
Less: Capitalized interest	(4,698,000)	[4]	(6,041,000)		(5,752,000)
Cash disbursed for construction in progress	136,431,000	[4]	173,643,000		176,874,000
Capital improvements to existing properties	34,926,000	[4]	67,026,000		49,336,000
Total cash invested in real property	482,051,000	[4]	1,201,774,000		3,368,722,000
Cash acquired from acquisition			2,031,000
Senior Housing Facilities Triple Net [Member] | Preliminary [Member]
Estimated Fair Value of Allocated Purchase Price of Asset and Liabilities
Total cash invested in real property	212,043,000
Medical Facilities [Member]
Estimated Fair Value of Allocated Purchase Price of Asset and Liabilities
Land and land improvements	14,515,000	[6]	68,619,000		48,342,000
Buildings and improvements	251,291,000	[6]	648,409,000		520,976,000
Acquired lease intangibles	9,432,000	[6]	115,233,000		60,609,000
Goodwill	0	[6]	0		0
Restricted cash	505,000	[6]	975,000		100,000
Receivables and other assets	344,000	[6]	4,469,000		3,053,000
Total assets acquired	276,087,000	[6],[7]	837,705,000	[7]	633,080,000	[7]
Secured debt	(55,884,000)	[6]	(267,527,000)		(72,225,000)
Accrued expenses and other liabilities	(1,041,000)	[6]	(25,928,000)		(34,214,000)
Total liabilities assumed	(56,925,000)	[6]	(293,455,000)		(106,439,000)
Capital in excess of par	0	[6]	0		0
Noncontrolling interests	(386,000)	[6]	(193,000)		(7,211,000)
Non-cash acquisition related activity	(12,056,000)	[6],[8]	(880,000)	[8]	0	[8]
Cash disbursed for acquisitions	206,720,000	[6]	543,177,000		519,430,000
Construction in progress additions	127,989,000		134,830,000		165,593,000
Less: Capitalized interest	(1,945,000)	[6]	(3,736,000)		(7,412,000)
Accruals	(18,752,000)		(18,327,000)		(33,451,000)
Cash disbursed for construction in progress	107,292,000	[6]	112,767,000		124,730,000
Capital improvements to existing properties	28,648,000	[6]	46,673,000		24,031,000
Total cash invested in real property	342,660,000	[6]	702,617,000		668,191,000
Cash acquired from acquisition			0		2,154,000
Contingent Consideration in Stock	12,500,000
Contingent Consideration Total	26,187,000		34,692,000
Medical Facilities [Member] | Preliminary [Member]
Estimated Fair Value of Allocated Purchase Price of Asset and Liabilities
Total cash invested in real property	222,147,000
Sunrise [Member]
Estimated Fair Value of Allocated Purchase Price of Asset and Liabilities
Cash disbursed for acquisitions	$ 2,456,011,000

[1] Includes an aggregate purchase price of $1,318,168,000 relating to the Revera Partnership for which the allocation of the purchase price consideration is preliminary and subject to change.

[2] Excludes $92,148,000, $20,691,000 and $38,952,000 of cash acquired during the years ended December 31, 2013, 2012 and 2011, respectively.

[3] Represents Sunrise loan and noncontrolling interest acquisitions during the first quarter of 2013.

[4] Includes acquisitions with an aggregate purchase price of $212,043,000 for which the allocation of the purchase price consideration is preliminary and subject to change.

[5] Excludes $2,031,000 of cash acquired during the year ended December 31, 2012.

[6] Includes acquisitions with an aggregate purchase price of $222,147,000 for which the allocation of the purchase price consideration is preliminary and subject to change.

[7] Excludes $2,154,000 of cash acquired during the year ended December 31, 2011.

[8] Represents non-cash consideration exchanged in an asset swap transaction during the year ended December 31, 2013.