Income Taxes Income Taxes - Unrecognized Tax Benefits Table (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2019	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of year	$ 1.1	$ 1.6	$ 2.5
Increases (decreases) for dispositions and other	0.5	0.0	(1.4)
Balance at end of year	$ 1.6	$ 1.6	$ 1.1