Shareholders' Equity - Accumulated Other Comprehensive Income (Loss) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2019 USD ($)
Summary of the components of accumulated other comprehensive income, net of tax
Balance at beginning of period	$ 905.1
Balance at end of period	870.1
Accumulated Other Comprehensive Income (Loss)
Summary of the components of accumulated other comprehensive income, net of tax
Balance at beginning of period	17.0
Other comprehensive income (loss) before reclassifications	(2.4)
Amounts reclassified from other comprehensive income (loss), net of tax of $0.1 million	0.8
Net current period other comprehensive income (loss)	(1.6)
Balance at end of period	15.4
Amount from reclassification, tax	0.1
Foreign Currency Translation
Summary of the components of accumulated other comprehensive income, net of tax
Balance at beginning of period	46.9
Other comprehensive income (loss) before reclassifications	(2.2)
Net current period other comprehensive income (loss)	(2.2)
Balance at end of period	44.7
Pension Liability Adjustment
Summary of the components of accumulated other comprehensive income, net of tax
Balance at beginning of period	(29.9)
Other comprehensive income (loss) before reclassifications	(0.2)
Amounts reclassified from other comprehensive income (loss), net of tax of $0.1 million	0.8
Net current period other comprehensive income (loss)	0.6
Balance at end of period	$ (29.3)