Investments in and Advances to Unconsolidated Joint Ventures - Schedule of Equity Method Investments (Details) $ in Thousands	Dec. 31, 2017 USD ($) joint_venture	Jan. 31, 2017	Dec. 31, 2016 USD ($)
Schedule of Equity Method Investments
Investments in and advances to unconsolidated joint ventures	$ 800,840		$ 571,491
CCRC JV
Schedule of Equity Method Investments
Investment ownership percentage	49.00%
Investments in and advances to unconsolidated joint ventures	$ 400,241		439,449
RIDEA II
Schedule of Equity Method Investments
Investment ownership percentage	40.00%	40.00%
Investments in and advances to unconsolidated joint ventures	$ 259,651		0
Life Science JVs
Schedule of Equity Method Investments
Investments in and advances to unconsolidated joint ventures	$ 65,581		67,879
Life Science JVs | Minimum
Schedule of Equity Method Investments
Investment ownership percentage	50.00%
Life Science JVs | Maximum
Schedule of Equity Method Investments
Investment ownership percentage	63.00%
Torrey Pines Science Center
Schedule of Equity Method Investments
Investment ownership percentage	50.00%
Britannia Biotech Gateway, LP
Schedule of Equity Method Investments
Investment ownership percentage	55.00%
LASDK, LP
Schedule of Equity Method Investments
Investment ownership percentage	63.00%
MBK JV
Schedule of Equity Method Investments
Investments in and advances to unconsolidated joint ventures	$ 38,005		38,909
Development JVs
Schedule of Equity Method Investments
Investments in and advances to unconsolidated joint ventures	$ 23,365		10,459
Number of unconsolidated joint ventures | joint_venture	4
Development JVs | Minimum
Schedule of Equity Method Investments
Investment ownership percentage	50.00%
Development JVs | Maximum
Schedule of Equity Method Investments
Investment ownership percentage	90.00%
Vintage Park Development JV
Schedule of Equity Method Investments
Investment ownership percentage	85.00%
Waldwick
Schedule of Equity Method Investments
Investment ownership percentage	85.00%
Otay Ranch
Schedule of Equity Method Investments
Investment ownership percentage	90.00%
MBK Development JV
Schedule of Equity Method Investments
Investment ownership percentage	50.00%
Medical Office JVs
Schedule of Equity Method Investments
Investments in and advances to unconsolidated joint ventures	$ 12,488		13,438
Number of unconsolidated joint ventures | joint_venture	3
Medical Office JVs | Minimum
Schedule of Equity Method Investments
Investment ownership percentage	20.00%
Medical Office JVs | Maximum
Schedule of Equity Method Investments
Investment ownership percentage	67.00%
HCP Ventures IV, LLC
Schedule of Equity Method Investments
Investment ownership percentage	20.00%
HCP Ventures III, LLC
Schedule of Equity Method Investments
Investment ownership percentage	30.00%
Suburban Properties, LLC
Schedule of Equity Method Investments
Investment ownership percentage	67.00%
K&Y JVs
Schedule of Equity Method Investments
Investment ownership percentage	80.00%
Investments in and advances to unconsolidated joint ventures	$ 1,283		1,342
Number of unconsolidated joint ventures | joint_venture	3
Advances to unconsolidated joint ventures, net
Schedule of Equity Method Investments
Investments in and advances to unconsolidated joint ventures	$ 226		$ 15