Income Taxes - Builtin Gain Tax (Details) - USD ($) $ in Millions	1 Months Ended		3 Months Ended	6 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015	Mar. 31, 2016	Jun. 30, 2017	Dec. 31, 2011	Dec. 31, 2016
Income taxes
Federal corporate income taxes exempt, minimum percentage of REIT taxable income distribution				100.00%
Tax Status Change or Tax Free Asset Acquisition from C Corporation Holding Period					10 years
Deferred tax liability for built-in gain tax	$ 17.4
Income taxes payable						$ 16.5
Maximum
Income taxes
Tax on sale of assets if sold within required holding period					$ 2,000.0
Period during which asset sales may occur			5 years
State
Income taxes
Deferred tax liability for built-in gain tax			$ 12.4
Certain states
Income taxes
Tax Status Change or Tax Free Asset Acquisition from C Corporation Holding Period				10 years
Federal
Income taxes
Tax Status Change or Tax Free Asset Acquisition from C Corporation Holding Period		5 years
Federal | U.S. Treasury proposed regulation issued in June 2016
Income taxes
Tax Status Change or Tax Free Asset Acquisition from C Corporation Holding Period	10 years
HCP, Inc. | HCRMC Properties C Corporation 2011 properties acquisition | Minimum
Income taxes
Intended holding period of acquired assets					10 years