Other Assets (Details)	3 Months Ended				0 Months Ended				3 Months Ended	12 Months Ended
	Mar. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Mar. 31, 2013 Delphis USD ($)	Dec. 31, 2012 Delphis USD ($)	Jun. 28, 2012 Four Seasons USD ($)	Jun. 28, 2012 Four Seasons GBP (£)	Mar. 31, 2013 Four Seasons GBP (£)	Dec. 31, 2012 Four Seasons GBP (£)	Mar. 31, 2013 HCP Ventures IV, LLC USD ($)	Dec. 31, 2012 HCP Ventures IV, LLC USD ($)
Other Assets
Straight-line rent assets, net of allowance of $33,767 and $33,521, respectively	$ 323,513,000	$ 306,294,000
Allowance on straight-line rent assets	33,767,000	33,521,000
Marketable debt securities	208,214,000	222,809,000
Leasing costs, net	93,678,000	93,763,000
Deferred financing costs, net	42,944,000	45,490,000
Goodwill	50,346,000	50,346,000
Marketable equity securities		24,829,000
Other	58,158,000	44,989,000
Total other assets	776,853,000	788,520,000
Cost basis of marketable equity securities		17,100,000
Other assets
Carrying value of interest accrued related to the Delphis loan			0	0
Additions related to accrued interest receivable			5,400,000	5,400,000
Loans receivables	291,870,000	276,030,000							8,000,000	10,000,000
Interest rate on marketable debt security					12.25%	12.25%			12.00%	12.00%
Percentage of counter party's partnership interest in the joint venture, by which loans receivable from unconsolidated joint venture are secured									80.00%
Realized gains on marketable debt securities sold	11,000,000
Marketable debt security, par value						138,500,000
Marketable debt security, par value, discounted					$ 214,900,000	£ 136,800,000	£ 136,900,000	£ 136,900,000
Yield to maturity (as a percent)					12.50%	12.50%