Segment Reporting (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Summary of information for reportable segments
Rental income	$ 347,847,000	$ 298,873,000	$ 684,303,000	$ 591,516,000
Resident fees and services	467,639,000	370,995,000	923,904,000	698,319,000
Interest income	8,933,000	7,640,000	17,527,000	16,696,000
Other income	2,027,000	1,025,000	2,520,000	1,725,000
Total revenues	826,446,000	678,533,000	1,628,254,000	1,308,256,000
Property operating expenses	343,754,000	277,958,000	685,185,000	530,780,000
Net Operating Income from Continuing Operations	482,692,000	400,575,000	943,069,000	777,476,000
Interest expense	121,065,000	109,465,000	241,898,000	218,303,000
Loss (gain) on derivatives, net	351,000	(2,716,000)	351,000	(407,000)
Depreciation and amortization	214,449,000	198,062,000	447,766,000	382,750,000
General and administrative	51,660,000	23,902,000	84,524,000	51,081,000
Transaction costs	7,040,000	28,136,000	7,993,000	94,116,000
Loss (gain) on extinguishment of debt, net	531,000	0	383,000	(308,000)
Income (loss) from continuing operations before income taxes and income from unconsolidated entities	87,596,000	43,726,000	160,154,000	31,941,000
Total assets	23,573,890,000		23,573,890,000		23,083,957,000
Percent Of Assets	1	1	1	1	1
Percent Of Revenues	1	1	1	1
Senior housing - triple net [Member]
Summary of information for reportable segments
Rental income	225,472,000	187,518,000	440,302,000	370,814,000
Resident fees and services	0	0	0	0
Interest income	5,666,000	5,433,000	11,106,000	11,276,000
Other income	325,000	199,000	446,000	408,000
Total revenues	231,463,000	193,150,000	451,854,000	382,498,000
Property operating expenses	0	0	0	0
Net Operating Income from Continuing Operations	231,463,000	193,150,000	451,854,000	382,498,000
Interest expense	8,879,000	3,247,000	17,769,000	9,055,000
Loss (gain) on derivatives, net	73,000	0	73,000	0
Depreciation and amortization	61,613,000	54,637,000	123,016,000	109,587,000
General and administrative	0	0	0	0
Transaction costs	4,007,000	11,211,000	4,283,000	11,705,000
Loss (gain) on extinguishment of debt, net	0		0	0
Income (loss) from continuing operations before income taxes and income from unconsolidated entities	156,891,000	124,055,000	306,713,000	252,151,000
Total assets	9,460,260,000		9,460,260,000
Senior housing - operating [Member]
Summary of information for reportable segments
Rental income	0	0	0	0
Resident fees and services	467,639,000	370,995,000	923,904,000	698,319,000
Interest income	11,000	0	11,000	757,000
Other income	1,264,000	0	1,318,000	0
Total revenues	468,914,000	370,995,000	925,233,000	699,076,000
Property operating expenses	310,029,000	248,972,000	618,213,000	473,475,000
Net Operating Income from Continuing Operations	158,885,000	122,023,000	307,020,000	225,601,000
Interest expense	28,833,000	19,412,000	56,312,000	38,482,000
Loss (gain) on derivatives, net	278,000	(2,716,000)	278,000	(407,000)
Depreciation and amortization	109,644,000	103,646,000	238,806,000	193,521,000
General and administrative	0	0	0	0
Transaction costs	1,660,000	16,799,000	2,290,000	82,124,000
Loss (gain) on extinguishment of debt, net	531,000		383,000	(308,000)
Income (loss) from continuing operations before income taxes and income from unconsolidated entities	17,939,000	(15,118,000)	8,951,000	(87,811,000)
Total assets	9,156,333,000		9,156,333,000
Medical facilities [Member]
Summary of information for reportable segments
Rental income	122,375,000	111,355,000	244,001,000	220,702,000
Resident fees and services	0	0	0	0
Interest income	3,256,000	2,207,000	6,410,000	4,663,000
Other income	362,000	662,000	665,000	1,072,000
Total revenues	125,993,000	114,224,000	251,076,000	226,437,000
Property operating expenses	33,725,000	28,986,000	66,972,000	57,305,000
Net Operating Income from Continuing Operations	92,268,000	85,238,000	184,104,000	169,132,000
Interest expense	8,122,000	9,506,000	17,730,000	18,364,000
Loss (gain) on derivatives, net	0	0	0	0
Depreciation and amortization	43,192,000	39,779,000	85,944,000	79,642,000
General and administrative	0	0	0	0
Transaction costs	1,373,000	126,000	1,420,000	287,000
Loss (gain) on extinguishment of debt, net	0		0	0
Income (loss) from continuing operations before income taxes and income from unconsolidated entities	39,581,000	35,827,000	79,010,000	70,839,000
Total assets	4,906,320,000		4,906,320,000
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	76,000	164,000	91,000	245,000
Total revenues	76,000	164,000	91,000	245,000
Property operating expenses	0	0	0	0
Net Operating Income from Continuing Operations	76,000	164,000	91,000	245,000
Interest expense	75,231,000	77,300,000	150,087,000	152,402,000
Loss (gain) on derivatives, net	0	0	0	0
Depreciation and amortization	0	0	0	0
General and administrative	51,660,000	23,902,000	84,524,000	51,081,000
Transaction costs	0	0	0	0
Loss (gain) on extinguishment of debt, net	0		0	0
Income (loss) from continuing operations before income taxes and income from unconsolidated entities	(126,815,000)	(101,038,000)	(234,520,000)	(203,238,000)
Total assets	50,977,000		50,977,000
International [Member]
Summary of information for reportable segments
Total revenues	130,524,000	87,024,000	257,233,000	147,568,000
Total assets	3,197,439,000		3,197,439,000		3,324,012,000
Percent Of Assets	0.136		0.136		0.144
Percent Of Revenues	0.158	0.128	0.158	0.113
United States [Member]
Summary of information for reportable segments
Total revenues	695,922,000	591,509,000	1,371,021,000	1,160,688,000
Total assets	$ 20,376,451,000		$ 20,376,451,000		$ 19,759,945,000
Percent Of Assets	0.864		0.864		0.856
Percent Of Revenues	0.842	0.872	0.842	0.887