Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Tax Contingency [Line Items]
Income tax expense (benefit)	$ 38.7	$ 38.7
Effective income tax rate reconciliation, percent	20.20%	23.40%
Scalar
Income Tax Contingency [Line Items]
Income tax expense (benefit)	$ (3.0)