Comprehensive Income (Loss) - Reclassifications from Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Accumulated Other Comprehensive Income Loss [Line Items]
Net realized loss	$ (5.0)	$ (5.4)	$ (10.7)	$ (9.4)
Reclassifications from Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income Loss [Line Items]
Reclassifications before tax	0.5	0.4	1.1	0.4
Income tax benefit	0.1	0.1	0.3	0.1
Reclassifications, net of tax	0.4	0.3	0.8	0.3
Reclassifications from Accumulated Other Comprehensive Loss | Change in Fair Value of Interest Rate Collars
Accumulated Other Comprehensive Income Loss [Line Items]
Net realized loss	$ 0.5	$ 0.4	$ 1.1	$ 0.4