Income Taxes Federal Statutory Rate Reconciliation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Federal statutory income tax rate	35.00%	35.00%	35.00%
State income taxes, net of federal income tax benefit	3.40%	3.30%	2.50%
Non-deductible expenses	0.30%	0.70%	2.00%
Domestic manufacturing deduction	(1.60%)	(1.40%)	(1.30%)
Unrecognized tax benefits	1.30%	0.50%	0.80%
Valuation allowance	0.00%	0.50%	0.50%
Stock option exercises	(2.60%)	(0.70%)	0.00%
Impact of Tax Act	(1.80%)	0.00%	0.00%
Other	0.00%	(0.90%)	(1.00%)
Total	34.00%	37.00%	38.50%
Unrecognized tax benefits that would impact effective tax rate	$ 12.4	$ 9.7	$ 8.7