Income Taxes Income Taxes - Additional Information (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Business Acquisition
Effective income tax rate	34.80%	35.20%
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability		$ 0.3
Rhiag and PGW
Business Acquisition
Deferred Tax Assets, Other	$ 29.6
Deferred Tax Liabilities, Other	$ 136.5