Derivative Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Notional amount of foreign currency derivative	$ 172.0	$ 188.6
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Notional amount of foreign currency derivative	0.0	71.8
Cash flow hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Notional amount of foreign currency derivative	$ 172.0	$ 116.8