Income and Other Taxes - Reconciliation of Amount Computed by Applying the Federal Statutory Income Tax Rate (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Federal statutory tax on earnings before income taxes	$ 58.8	$ 39.2	$ 26.8
State income taxes, net of federal income tax benefit	3.5	1.8	1.4
Non-deductible expense	3.3	2.6	1.0
Non-deductible acquisition-related charges	1.7	6.6	1.3
Manufacturing deduction	0.0	(2.0)	0.0
Valuation allowance	(0.2)	0.0	0.0
Windfall deduction from equity compensation	(4.9)	0.0	0.0
Other	(2.2)	(1.3)	(0.4)
Income tax expense (benefit)	$ 60.0	$ 46.9	$ 30.1