Postretirement Benefit Plans - Balance Sheet Items (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Amounts recognized on the Consolidated Balance Sheets:
Current liabilities	$ (5.7)	$ (9.1)
Postretirement Benefit Plans [Member]
Amounts recognized on the Consolidated Balance Sheets:
Current liabilities	(7.5)	(14.5)
Non-current liabilities	(131.5)	(136.1)
Total	$ (139.0)	$ (150.6)