Segment Reporting (Details)	3 Months Ended			6 Months Ended
	Jun. 30, 2015 USD ($)		Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($)		Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Summary of information for reportable segments
Rental income	$ 396,626,000		$ 347,847,000	$ 776,213,000		$ 684,303,000
Resident fees and services	535,553,000		467,639,000	1,028,063,000		923,904,000
Interest income	20,576,000		8,933,000	37,570,000		17,527,000
Other income	4,414,000		2,027,000	9,500,000		2,520,000
Total revenues	957,169,000		826,446,000	1,851,346,000		1,628,254,000
Property operating expenses	398,354,000		343,754,000	774,815,000		685,185,000
Net Operating Income from Continuing Operations	558,815,000	[1]	482,692,000	1,076,531,000		943,069,000
Interest expense	118,861,000		121,065,000	239,942,000		241,898,000
Loss (gain) on derivatives, net	0		(351,000)	58,427,000	[2]	(351,000)
Depreciation and amortization	208,802,000		214,449,000	397,631,000		447,766,000
General and administrative	38,474,000		51,660,000	73,612,000		84,524,000
Transaction costs	12,491,000		7,040,000	61,045,000		7,993,000
Loss (gain) on extinguishment of debt, net	(18,887,000)		(531,000)	(34,288,000)		(383,000)
Impairment of Asset	0		0	2,220,000		0
Other expenses	10,583,000		0	10,583,000		0
Income (loss) from continuing operations before income taxes and income from unconsolidated entities	150,717,000		87,596,000	315,637,000		160,154,000
Income tax (expense) benefit	(7,417,000)		(1,569,000)	(7,113,000)		(3,830,000)
(Loss) income from unconsolidated entities	(2,952,000)		(11,516,000)	(15,600,000)		(17,073,000)
Income (loss) from continuing operations	140,348,000		74,511,000	292,924,000		139,251,000
Discontinued Operation, Amount of Other Income (Loss) from Disposition of Discontinued Operation, Net of Tax	0		264,000	0		724,000
Discontinued operations, net	0		6,675,000	0		7,135,000
Gain (loss) on real estate dispositions, net	190,111,000		6,668,000	246,956,000		6,668,000
Net income	330,459,000		$ 87,854,000	539,880,000		$ 153,054,000
Total assets	$ 27,407,482,000			$ 27,407,482,000			$ 25,014,296,000
Percent Of Assets	1			1
Percent Of Revenues	1		1	1		1
Triple Net [Member]
Summary of information for reportable segments
Rental income	$ 279,990,000		$ 248,134,000	$ 544,396,000		$ 485,852,000
Resident fees and services	0		0	0		0
Interest income	18,189,000		7,980,000	32,888,000		15,700,000
Other income	970,000		325,000	4,853,000		468,000
Total revenues	299,149,000		256,439,000	582,137,000		502,020,000
Property operating expenses			447,000	0		690,000
Net Operating Income from Continuing Operations	299,149,000		255,992,000	582,137,000		501,330,000
Interest expense	2,679,000		8,655,000	12,706,000		17,769,000
Loss (gain) on derivatives, net	0		73,000	(58,427,000)		73,000
Depreciation and amortization	72,402,000		67,372,000	142,434,000		134,640,000
General and administrative	0		0	0		0
Transaction costs	7,579,000		4,007,000	43,750,000		4,283,000
Loss (gain) on extinguishment of debt, net	(102,000)		0	10,235,000		0
Provision for loan losses			0
Impairment of Asset				2,220,000
Income (loss) from continuing operations before income taxes and income from unconsolidated entities	216,591,000		175,885,000	429,219,000		344,565,000
Income tax (expense) benefit	(3,121,000)		(438,000)	(2,703,000)		(793,000)
(Loss) income from unconsolidated entities	1,453,000		1,423,000	2,846,000		2,804,000
Income (loss) from continuing operations	214,923,000		176,870,000	429,362,000		346,576,000
Discontinued Operation, Amount of Other Income (Loss) from Disposition of Discontinued Operation, Net of Tax			6,675,000
Discontinued operations, net				0		7,135,000
Gain (loss) on real estate dispositions, net	0		5,762,000	54,097,000		5,762,000
Net income	214,923,000		189,307,000	483,459,000		359,473,000
Total assets	12,191,264,000			12,191,264,000
Senior housing - operating [Member]
Summary of information for reportable segments
Rental income	0		0	0		0
Resident fees and services	535,553,000		467,639,000	1,028,063,000		923,904,000
Interest income	1,042,000		11,000	2,073,000		11,000
Other income	3,210,000		1,264,000	4,229,000		1,318,000
Total revenues	539,805,000		468,914,000	1,034,365,000		925,233,000
Property operating expenses	360,569,000		310,029,000	699,076,000		618,213,000
Net Operating Income from Continuing Operations	179,236,000		158,885,000	335,289,000		307,020,000
Interest expense	38,796,000		28,833,000	73,255,000		56,312,000
Loss (gain) on derivatives, net	0		278,000	0		278,000
Depreciation and amortization	88,844,000		109,644,000	165,479,000		238,806,000
General and administrative	0		0	0		0
Transaction costs	3,937,000		1,660,000	15,979,000		2,290,000
Loss (gain) on extinguishment of debt, net	0		531,000	0		383,000
Other expenses	0			0
Income (loss) from continuing operations before income taxes and income from unconsolidated entities	47,659,000		17,939,000	80,576,000		8,951,000
Income tax (expense) benefit	(3,449,000)		(801,000)	(3,982,000)		(2,444,000)
(Loss) income from unconsolidated entities	(6,083,000)		(15,496,000)	(21,156,000)		(23,457,000)
Income (loss) from continuing operations	38,127,000		1,642,000	55,438,000		(16,950,000)
Net income	38,127,000		1,642,000	55,438,000		(16,950,000)
Total assets	10,432,990,000			10,432,990,000
Outpatient Medical [Member]
Summary of information for reportable segments
Rental income	116,636,000		99,713,000	231,817,000		198,451,000
Resident fees and services	0		0	0		0
Interest income	1,345,000		942,000	2,609,000		1,816,000
Other income	195,000		362,000	356,000		643,000
Total revenues	118,176,000		101,017,000	234,782,000		200,910,000
Property operating expenses	37,785,000		33,278,000	75,739,000		66,282,000
Net Operating Income from Continuing Operations	80,391,000		67,739,000	159,043,000		134,628,000
Interest expense	7,184,000		8,346,000	14,809,000		17,730,000
Loss (gain) on derivatives, net	0		0	0		0
Depreciation and amortization	47,556,000		37,433,000	89,718,000		74,320,000
General and administrative	0		0	0		0
Transaction costs	975,000		1,373,000	1,316,000		1,420,000
Loss (gain) on extinguishment of debt, net	0			0		0
Income (loss) from continuing operations before income taxes and income from unconsolidated entities	24,676,000		20,587,000	53,200,000		41,158,000
Income tax (expense) benefit	(161,000)		(330,000)	305,000		(593,000)
(Loss) income from unconsolidated entities	1,678,000		2,557,000	2,710,000		3,580,000
Income (loss) from continuing operations	26,193,000		22,814,000	56,215,000		44,145,000
Discontinued operations, net				0
Gain (loss) on real estate dispositions, net	190,111,000		906,000	192,859,000		906,000
Net income	216,304,000		23,720,000	249,074,000		45,051,000
Total assets	4,701,830,000			4,701,830,000
Non Segment Corporate [Member]
Summary of information for reportable segments
Rental income	0		0	0		0
Resident fees and services	0		0	0		0
Interest income	0		0	0		0
Other income	39,000		76,000	62,000		91,000
Total revenues	39,000		76,000	62,000		91,000
Property operating expenses	0		0	0		0
Net Operating Income from Continuing Operations	39,000		76,000	62,000		91,000
Interest expense	70,202,000		75,231,000	139,172,000		150,087,000
Loss (gain) on derivatives, net	0		0	0		0
Depreciation and amortization	0		0	0		0
General and administrative	38,474,000		51,660,000	73,612,000		84,524,000
Transaction costs	0		0	0		0
Loss (gain) on extinguishment of debt, net	18,989,000		0	24,053,000		0
Other expenses	10,583,000	[3]		10,583,000
Income (loss) from continuing operations before income taxes and income from unconsolidated entities	(138,209,000)		(126,815,000)	(247,358,000)		(234,520,000)
Income tax (expense) benefit	(686,000)		0	(733,000)		0
(Loss) income from unconsolidated entities	0		0	0		0
Income (loss) from continuing operations	(138,895,000)		(126,815,000)	(248,091,000)		(234,520,000)
Net income	(138,895,000)		(126,815,000)	(248,091,000)		(234,520,000)
Total assets	81,398,000			81,398,000
International [Member]
Summary of information for reportable segments
Total revenues	186,138,000		$ 130,524,000	335,178,000		$ 257,233,000
Total assets	$ 5,134,019,000			$ 5,134,019,000			$ 4,285,819,000
Percent Of Assets	0.187			0.187			0.171
Percent Of Revenues	0.194		0.158	0.181		0.158
United States [Member]
Summary of information for reportable segments
Total revenues	$ 771,031,000		$ 695,922,000	$ 1,516,168,000		$ 1,371,021,000
Total assets	$ 22,273,463,000			$ 22,273,463,000			$ 20,728,477,000
Percent Of Assets	0.813			0.813			0.829
Percent Of Revenues	0.806		0.842	0.819		0.842

[1] (1)     Genesis Healthcare is in our triple-net segment. Sunrise Senior Living and Revera are in our seniors housing operating segment. Brookdale Senior Living and Benchmark Senior Living are in both our triple-net and seniors housing operating segments.

[2] (1) In April 2011, we completed the acquisition of substantially all of the real estate assets of privately-owned Genesis Healthcare Corporation. In conjunction with this transaction, we received the option to acquire an ownership interest in Genesis Healthcare. In February 2015, Genesis Healthcare closed on a transaction to merge with Skilled Healthcare Group to become a publicly traded company which required us to record the value of the derivative asset due to the net settlement feature.

[3] Due to termination of our investment in a strategic medical office partnership and costs associated with a retiring executive officer.