Acquisitions, Dispositions and Other Significant Transactions - Ventas Lease Portfolio Restructuring (Details) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Apr. 30, 2018	Jun. 30, 2019 USD ($) lease community	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) lease community	Jun. 30, 2018 USD ($)	Apr. 01, 2018 community
Business Acquisition [Line Items]
Number of communities leased | lease		244		244
Loss on facility lease termination and modification, net | $		$ (1,797)	$ (146,467)	$ (2,006)	$ (146,467)
Ventas, Inc | Master Lease And Security Agreement
Business Acquisition [Line Items]
Number of communities leased | community						128
Management percent fee	5.00%
Loss on facility lease termination and modification, net | $			$ 125,700
Number of communities exercised to market for sale | community				28
Option to terminate, rent reduction percentage						6.25%
Number of communities exercised to market for sale and sold | community		5
Option to terminate, reduction of rent for terminating communities | $		$ 1,500