Adoption of Accounting Principles and Recently Issued Accounting Pronouncements (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restricted cash	$ 3.7	$ 2.9
Accounting Standards Update 2015-03 - Simplifying the Presentation of Debt Issuance Costs [Member] | Other Deferred Charges [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New accounting pronouncement, effect of adoption, decrease in assets and liabilities (debt issuance costs)	3.9	4.3
Accounting Standards Update 2015-03 - Simplifying the Presentation of Debt Issuance Costs [Member] | Long-term Debt [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New accounting pronouncement, effect of adoption, decrease in assets and liabilities (debt issuance costs)	3.9	$ 4.3
Accounting Standards Update 2016-18 - Restricted Cash [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restricted cash	$ 5.1