Background and Basis of Presentation - Marketable Securities (Details) $ in Millions	Sep. 30, 2016 USD ($)
Marketable securities
Cost of marketable securities	$ 3.4
Pension Benefits
Held to maturity
Investments restricted to the payment of post-retirement employee benefits	1.7
Prepaid Expenses and Other Current Assets | Pension Benefits
Held to maturity
Investments restricted to the payment of post-retirement employee benefits	0.6
Other Assets | Pension Benefits
Held to maturity
Investments restricted to the payment of post-retirement employee benefits	1.1
Fair Value | Level 1 | Other Assets
Marketable securities
Fair value of marketable securities	$ 3.5