Income Taxes (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended		12 Months Ended
	Jan. 01, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Effective income tax rates (in percentage)		29.70%	40.60%	24.30%	39.80%
Reclassification from accumulated other comprehensive income to retained earnings	$ 0.2			$ 0.2
Repricing of deferred tax balance						$ 9.1
Provisional income tax payable	$ 0.2
Provisional income tax expense		$ 8.2		$ 8.2		$ 10.2