Leases - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) property	Dec. 31, 2017 USD ($) property	Dec. 31, 2016 USD ($)	Sep. 30, 2013 property
Capital Leased Assets [Line Items]
Properties subject to direct financing leases (in properties) | property	29	29
Income from direct financing leases	$ 54,274	$ 54,217	$ 59,580
Net investment in direct financing leases	713,818	714,352
Rent expense	10,000	10,000	10,000
DFL Portfolio
Capital Leased Assets [Line Items]
Income from direct financing leases	14,000	13,000	13,000
Cash income	19,000	18,000	$ 18,000
DFL Portfolio | Senior housing
Capital Leased Assets [Line Items]
Properties subject to direct financing leases (in properties) | property				14
Net investment in direct financing leases	$ 351,000	$ 356,000