Derivative Instruments - Cash Flow Hedges and Offsetting of Derivatives (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Derivatives, Notional Amount [Line Items]
Notional amount of foreign currency derivatives	$ 296.5		$ 296.5		$ 172.0
Foreign exchange contract [Member] | Cash flow hedging [Member]
Derivatives, Notional Amount [Line Items]
Derivative instruments, gain (loss) recognized in other comprehensive income (loss), Effective portion	$ 3.8	$ 1.5	$ 10.8	$ 4.5