Derivative Financial Instruments Cross Currency Swap (Details) € in Millions, AUD in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 01, 2016 AUD	Dec. 01, 2016 EUR (€)
Currency Swap [Member]
Derivatives [Line Items]
Derivative, Notional Amount			AUD 248.9	€ 171.7
Derivative, Maturity Date	Jun. 30, 2019
Currency Swap 1 [Member]
Derivatives [Line Items]
Derivative, Notional Amount			123.9	85.5
Currency Swap 2 [Member]
Derivatives [Line Items]
Derivative, Notional Amount			125.0	€ 86.3
BBR Interest rate [Member] | Currency Swap 1 [Member]
Derivatives [Line Items]
Derivative, Description of Terms	Australian dollar BBR plus 4.50%
BBR Interest rate [Member] | Currency Swap 2 [Member]
Derivatives [Line Items]
Derivative, Description of Terms	Australian dollar BBR plus 4.50%
EURIBOR Interest Rate [Member] | Currency Swap 1 [Member]
Derivatives [Line Items]
Derivative, Description of Terms	EURIBOR plus 2.68%
EURIBOR Interest Rate [Member] | Currency Swap 2 [Member]
Derivatives [Line Items]
Derivative, Description of Terms	EURIBOR plus 2.90%
Intercompany Loan [Member]
Derivatives [Line Items]
Debt Instrument, Face Amount | AUD			AUD 248.9
Interest Expense [Member] | Currency Swap [Member]
Derivatives [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ 3.5
Other (expense)/income, net
Derivatives [Line Items]
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments, Net of Foreign Currency Transaction Gain (Loss) on Intercompany Loan	$ 2.5	$ 3.3