Real Property Acquisitions and Development - Construction Activity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Real property acquisitions and development [Line Items]
Total construction in progress conversions	$ 0	$ 85,977
Seniors Housing Operating
Real property acquisitions and development [Line Items]
Total development projects	0	36,218
Triple-net
Real property acquisitions and development [Line Items]
Total development projects	$ 0	$ 49,759