Segment Information (Income Statement by Segment) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenues:
Rental income																	$ 1,325,984	$ 1,178,849	$ 793,802
Resident fees and services																	1,406,005	1,227,124	865,800
Medical office building and other services revenue																	17,809	20,741	36,471
Income from loans and investments																	58,208	39,913	34,415
Interest and other income																	2,047	1,106	1,216
Total revenues	732,856	[1]	710,924	[1]	683,764	[1]	682,509	[1]	655,730	[2]	637,218	[2]	610,188	[2]	564,597	[2]	2,810,053	2,467,733	1,731,704
Less:
Interest and other income																	2,047	1,106	1,216
Property-level operating expenses																	1,109,632	966,422	645,082
Medical office building services costs																	8,315	9,883	27,082
Segment NOI																	1,690,059	1,490,322	1,058,324
Income (loss) from unconsolidated entities																	(508)	18,154	(52)
Segment profit																	1,689,551	1,508,476	1,058,272
Interest and other income																	2,047	1,106	1,216
Interest expense																	(334,484)	(288,276)	(223,804)
Depreciation and amortization																	(721,959)	(714,505)	(444,193)
General, administrative and professional fees																	(115,106)	(98,510)	(74,537)
Loss on extinguishment of debt																	(1,201)	(37,640)	(27,604)
Litigation proceeds, net																	0	0	202,259
Merger-related expenses and deal costs																	(21,634)	(63,183)	(153,923)
Other																	(18,732)	(6,940)	(7,270)
Income tax benefit																	11,828	6,282	30,660
Discontinued operations	102	[1]	(8,972)	[1]	(18,315)	[1]	(8,236)	[1]	(15,172)	[2]	(3,855)	[2]	30,612	[2]	43,380	[2]	(35,421)	54,965	2,185
Net income																	454,889	361,775	363,261
Triple Net Leased Properties
Revenues:
Rental income																	875,877	818,000	627,723
Medical office building and other services revenue																	4,469	4,438	2,217
Total revenues																	880,346	822,438	629,940
Less:
Segment NOI																	880,346	822,438	629,940
Income (loss) from unconsolidated entities																	475	1,313	295
Segment profit																	880,821	823,751	630,235
Senior Living Operations
Revenues:
Resident fees and services																	1,406,005	1,227,124	865,800
Total revenues																	1,406,005	1,227,124	865,800
Less:
Property-level operating expenses																	956,684	841,022	588,095
Segment NOI																	449,321	386,102	277,705
Income (loss) from unconsolidated entities																	(1,980)	(48)	0
Segment profit																	447,341	386,054	277,705
MOB Operations
Revenues:
Rental income																	450,107	360,849	166,079
Medical office building and other services revenue																	12,077	16,303	34,254
Total revenues																	462,184	377,152	200,333
Less:
Property-level operating expenses																	152,948	125,400	56,987
Medical office building services costs																	8,315
Segment NOI																	300,921	241,869	116,264
Income (loss) from unconsolidated entities																	1,451	16,889	(347)
Segment profit																	302,372	258,758	115,917
All Other
Revenues:
Medical office building and other services revenue																	1,263
Income from loans and investments																	58,208	39,913	34,415
Interest and other income																	2,047	1,106	1,216
Total revenues																	61,518	41,019	35,631
Less:
Interest and other income																	2,047	1,106	1,216
Segment NOI																	59,471	39,913	34,415
Income (loss) from unconsolidated entities																	(454)	0	0
Segment profit																	59,017	39,913	34,415
Interest and other income																	$ 2,047	$ 1,106	$ 1,216

[1] The amounts presented for the three months ended March 31, 2013, June 30, 2013 and September 30, 2013 differ from the amounts previously reported in our Quarterly Reports on Form 10-Q as a result of discontinued operations consisting of properties sold in 2013 or classified as held for sale as of December 31, 2013.

[2] The amounts presented for the three months ended March 31, 2012, June 30, 2012, September 30, 2012 and December 31, 2012 differ from the amounts previously reported in our Annual Report on Form 10-K for the year ended December 31, 2012 as a result of discontinued operations consisting of properties sold in 2013 or classified as held for sale as of December 31, 2013.