Credit Facilities - Revolving Credit Facility - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Line of Credit Facility [Line Items]
Total deferred finance costs, net	$ 2.5		$ 2.5		$ 3.8
Interest expense recorded from amortization of deferred financing costs	0.2	$ 0.4	0.3	$ 1.0
Revolving Credit Facility and the 2018 Credit Facility
Line of Credit Facility [Line Items]
Interest expense recorded from amortization of deferred financing costs	0.3	0.3	0.6	0.5
Weighted-average interest rates					3.06%
Line of credit facility, unused borrowing capacity	400.0		400.0		$ 354.0
Revolving Credit Facility and the 2018 Credit Facility | Prepaid Expenses and Other Assets
Line of Credit Facility [Line Items]
Total deferred finance costs, net	3.1		3.1		$ 3.5
Revolving Credit Facility
Line of Credit Facility [Line Items]
Interest expense on borrowings and unused facility fees	$ 0.5	$ 0.3	$ 0.9	$ 1.0