Debt (Details)				12 Months Ended	0 Months Ended		0 Months Ended	12 Months Ended														0 Months Ended							12 Months Ended
	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2013 Line of Credit and Term Loan USD ($)	Dec. 31, 2013 Bank Line of Credit USD ($)	Jul. 30, 2012 2012 Term Loan GBP (£)	Dec. 31, 2013 2012 Term Loan USD ($)	Jul. 30, 2012 2012 Term Loan Interest-rate swap contracts	Dec. 31, 2013 Senior Unsecured Notes USD ($)	Dec. 31, 2013 Senior Unsecured Notes Minimum	Dec. 31, 2013 Senior Unsecured Notes Maximum	Dec. 31, 2013 Senior Unsecured Notes Debt maturing in 2014 USD ($)	Dec. 31, 2013 Senior Unsecured Notes Debt maturing in 2015 USD ($)	Dec. 31, 2013 Senior Unsecured Notes Debt maturing in 2016 USD ($)	Dec. 31, 2013 Senior Unsecured Notes Debt maturing in 2017 USD ($)	Dec. 31, 2013 Senior Unsecured Notes Debt maturing in 2018 USD ($)	Dec. 31, 2013 Senior Unsecured Notes Debt instrument maturing in 2019 USD ($)	Dec. 31, 2013 Senior Unsecured Notes Debt instrument maturing in 2020 USD ($)	Dec. 31, 2013 Senior Unsecured Notes Debt instrument maturing in 2021 USD ($)	Dec. 31, 2013 Senior Unsecured Notes Debt instrument maturing in 2022 USD ($)	Dec. 31, 2013 Senior Unsecured Notes Debt instrument maturing in 2023 USD ($)	Dec. 31, 2013 Senior Unsecured Notes Debt instrument maturing in 2041 USD ($)	Nov. 12, 2013 Senior Unsecured, 4.25% notes due 2023 USD ($)	Nov. 19, 2012 Senior Unsecured, 2.625% notes due 2020 USD ($)	Jul. 23, 2012 Senior Unsecured, 3.15% notes due 2022 USD ($)	Jan. 23, 2012 Senior Unsecured, 3.75% notes due 2019 USD ($)	Dec. 16, 2013 Senior unsecured notes, 5.65% USD ($)	Feb. 28, 2013 Senior Unsecured, 5.625% USD ($)	Jun. 25, 2012 Senior Unsecured, 6.45% notes due 2012 USD ($)	Dec. 31, 2013 Mortgage Debt USD ($) item	Dec. 31, 2013 Mortgage Debt Minimum	Dec. 31, 2013 Mortgage Debt Maximum	Dec. 31, 2013 Mortgage Debt Debt maturing in 2014 USD ($)	Dec. 31, 2013 Mortgage Debt Debt maturing in 2015 USD ($)	Dec. 31, 2013 Mortgage Debt Debt maturing in 2016 USD ($)	Dec. 31, 2013 Mortgage Debt Debt maturing in 2017 USD ($)	Dec. 31, 2013 Mortgage Debt Debt maturing in 2018 USD ($)	Dec. 31, 2013 Mortgage Debt Thereafter USD ($)	Dec. 31, 2013 Other Debt USD ($) item
Debt Instrument
Line of credit facility, maximum borrowing capacity				$ 1,500,000,000
Length of debt instrument extension period				1 year	1 year
Debt instrument, variable rate basis				LIBOR	GBP LIBOR
Debt instrument, basis spread on variable rate (as a percent)				1.075%	1.20%
Debt instrument, facility fee (as a percent)				0.175%
Line of credit facility additional aggregate amount, maximum				500,000,000
Line of credit facility, amount outstanding				0
Debt instrument, covenant debt to assets (as a percent)			60.00%
Debt instrument, covenant secured debt to assets (as a percent)			30.00%
Debt instrument, covenant unsecured debt to unencumbered assets (as a percent)			60.00%
Debt instrument, covenant minimum fixed charge coverage ratio			1.5
Debt instrument, covenant net worth			9,200,000,000
Debt instrument, effective interest rate (as a percent)																						4.307%	2.667%	3.28%	3.83%
Weighted-average interest rate (as a percent)								4.97%			3.21%	6.57%	5.10%	6.03%	6.83%	3.96%	2.79%	5.60%	3.39%	4.41%	6.88%								6.19%			5.80%	5.96%	6.89%	6.20%	5.90%	5.09%
Weighted-average maturity								6 years																					3 years
Issuance of senior unsecured notes																						800,000,000	800,000,000	300,000,000	450,000,000
Debt issuance price as a percentage of principal amount																						99.54%	99.729%	98.888%	99.523%
Net proceeds from issuance of senior unsecured notes																						789,000,000	793,000,000	294,000,000	444,000,000
Repayment of senior unsecured notes																										400,000,000	150,000,000	250,000,000
Stated interest rate (as a percent)									1.21%	6.98%												4.25%	2.625%	3.15%	3.75%	5.65%	5.625%	6.45%		0.69%	8.69%
2014	666,525,000							487,000,000																					179,525,000
2015	708,421,000							400,000,000																					308,421,000
2016	1,418,596,000					226,858,000		900,000,000																					291,738,000
2017	1,300,477,000							750,000,000																					550,477,000
2018	606,583,000							600,000,000																					6,583,000
Thereafter	3,915,242,000							3,850,000,000																					65,242,000
Debt instrument principal outstanding, total	8,615,844,000					226,858,000		6,987,000,000			487,000,000	400,000,000	900,000,000	750,000,000	600,000,000	450,000,000	800,000,000	1,200,000,000	300,000,000	800,000,000	300,000,000								1,401,986,000			179,525,000	308,421,000	291,738,000	550,477,000	6,583,000	65,242,000
Discounts, net	(29,126,000)							(23,625,000)																					(5,501,000)
Debt instruments, carrying amount	8,586,718,000				137,000,000	226,858,000		6,963,375,000																					1,396,485,000
Number of healthcare facilities used to secure debt																													126
Debt instrument, collateral, healthcare facilities carrying value																													1,800,000,000
Maturity period of debt instruments					4 years
Term of the interest rate swap agreement							4 years
Debt instrument, fixed interest rate (as a percent)							1.81%
Portion of other debt and occupancy fee deposits excluded from schedule of debt maturities	$ 74,909,000	$ 81,958,000																																				$ 75,000,000
Number of CCRC issuing non-interest life care bonds																																						2
Non-interest bearing occupancy fee deposits																																						2