Accumulated Other Comprehensive Income (Loss) - Derivative Gain (Loss) Recognized in OCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total before tax	$ (4.1)
Total before tax		$ 0.4	$ (0.4)
Tax (expense) benefit	(1.1)
Tax (expense) benefit		0.0	0.0
Net of tax	(3.0)
Net of tax		0.4	(0.4)
Interest Rate Caps
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total before tax	$ (4.1)
Total before tax		$ 0.4	$ (0.4)