Derivative Instruments (Details) € in Millions, £ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 EUR (€)	Jun. 30, 2015 GBP (£)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative financial instruments revaluation, net of tax	$ 0	$ (100,000)	$ 0	$ (100,000)
Foreign Exchange Forward [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Foreign currency forward contract	139,000,000		139,000,000
Foreign Exchange Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative financial instruments revaluation, net of tax	1,400,000	300,000	1,400,000.0	500,000
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gains (losses) recorded to other comprehensive income related to foreign currency hedges	0	$ 200,000	0	$ 200,000
United States of America, Dollars [Member] | Foreign Exchange Forward [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Foreign currency forward contract	$ 125,000,000		$ 125,000,000
United Kingdom, Pounds [Member] | Foreign Exchange Forward [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Foreign currency forward contract | £						£ 5.9
Euro Member Countries, Euro [Member] | Foreign Exchange Forward [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Foreign currency forward contract | €					€ 4.2