XML 56 R40.htm IDEA: XBRL DOCUMENT v3.8.0.1
ACCOUNTING POLICIES - Redeemable OP Unitholder and Noncontrolling Interest (Details)
shares in Millions, $ in Millions
3 Months Ended
Mar. 31, 2018
USD ($)
shares
Dec. 31, 2017
USD ($)
Redeemable Noncontrolling Interest    
Fair value of operating partnership units exceeding cost | $ $ 120.3 $ 146.3
NHP/PMB L.P.    
Redeemable Noncontrolling Interest    
Unit conversion factor for common stock 0.9051  
NHP/PMB L.P. | Limited Partner | Class A    
Redeemable Noncontrolling Interest    
Limited partners' units outstanding 2.7  
Percentage of ownership interest on total units outstanding 27.00%  
NHP/PMB L.P. | General Partner | Class B    
Redeemable Noncontrolling Interest    
Percentage of ownership interest on total units outstanding 73.00%  
General partners' units outstanding 7.2