Brookdale Lease Amendments and Terminations and the Formation of Two RIDEA Joint Ventures ("Brookdale Transaction") - Components of Brookdale Transaction and NNN Lease Restructing (Details) $ in Millions	Aug. 29, 2014 USD ($) property item	Dec. 31, 2016 property
Lease Amendments And Terminations And Joint Venture Formations.
Number Of Properties Contributed To Joint Venture | item	48
Brookdale Senior Living | RIDEA JV
Business Combination, Consideration Transferred.
Number of properties		49
Brookdale Senior Living | NNN-leased Portfolio
Lease Amendments And Terminations And Joint Venture Formations.
Number of facilities for which existing lease agreement is amended	153
Number of properties with purchase options cancelled on amendment	30
Business Combination, Consideration Transferred.
Number of properties		153
Consideration paid to terminate purchase options | $	$ 129
Rent concessions | $	76
Net consideration paid | $	$ 53