Operations and Significant Accounting Policies - New Accounting Standards (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Presentation of Debt Issuance Costs [Member] | Total Assets [Member]
New Accounting Standards [Line Items]
Effect of the Adoption		$ (12.6)
Presentation of Debt Issuance Costs [Member] | Total Liabilities [Member]
New Accounting Standards [Line Items]
Effect of the Adoption		$ (12.6)
Income Tax Expense (Benefit) [Member] | Maximum [Member] | Improvements to Employee Share-Based Payment Accounting [Member]
New Accounting Standards [Line Items]
Effect of the Adoption	$ 1.0