Rent Expense - Additional Information (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($) properties healthcareproperty	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) properties healthcareproperty	Sep. 30, 2016 USD ($)
Operating Leased Assets [Line Items]
Number of properties subject to parking lease	2		2
Number of properties subject to air space lease | healthcareproperty	1		1
Number of properties subject to ground leases	75		75
Number of office space leases	4		4
Maximum lease terms			98 years
Operating Expense | Parking, Air And Ground Leases
Operating Leased Assets [Line Items]
Rent expenses for parking, air, and ground leases | $	$ 0.6	$ 0.5	$ 1.8	$ 1.3