Brookdale Lease Amendments and Terminations and the Formation of Two RIDEA Joint Ventures (“Brookdale Transaction”) (Details) $ in Thousands		1 Months Ended	9 Months Ended
	Aug. 29, 2014 property item	Aug. 31, 2014 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)
Net Gain Recognized on Lease Terminations
Net gain on contract termination | $		$ 38,000	$ 1,103	$ 38,001
Gain based on fair value of net consideration received for lease terminations | $		108,000
Charges related to lease termination write-offs | $		$ 70,000
Brookdale Senior Living
Lease Amendments and Terminations and Joint Venture Formations - disclosures
Number of components in agreement | item	3
Number of facilities for which existing lease agreement is amended	153
Number of properties with purchase options cancelled on amendment	30
Number of facilities for which existing lease agreement is terminated	49
Number of properties with purchase options cancelled on termination	19
RIDEA II | RIDEA I OpCo
Lease Amendments and Terminations and Joint Venture Formations - disclosures
Number of properties contributed to joint venture	48
RIDEA II | Brookdale Senior Living | RIDEA I OpCo
Lease Amendments and Terminations and Joint Venture Formations - disclosures
Noncontrolling interest (as a percent)			20.00%
CCRC JV | RIDEA I OpCo
Lease Amendments and Terminations and Joint Venture Formations - disclosures
Number of retirement communities	14
Ownership percentage (as a percent)	49.00%
CCRC JV | Brookdale Senior Living | RIDEA I OpCo
Lease Amendments and Terminations and Joint Venture Formations - disclosures
Ownership percentage (as a percent)	51.00%