Employee Benefits Deferred Compensation Plan (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred Compensation Liability, Current and Noncurrent	$ 6.1	$ 5.6
Deferred Compensation Arrangement with Individual, Compensation Expense	0.6	(0.1)	$ 0.6
Deferred Compensation Plan Assets	6.1	5.6
Deferred Compensation Plan Assets, Income	$ 0.6	$ (0.1)	$ 0.6