Fair Value of Financial Instruments - Derivatives (Details)	3 Months Ended			3 Months Ended
	Mar. 31, 2014 USD ($) contract	Mar. 31, 2013 USD ($)	Dec. 31, 2013 USD ($) contract	Mar. 31, 2014 Forward Contracts USD ($)	Mar. 31, 2013 Forward Contracts USD ($)	Mar. 31, 2014 Forward Contracts EUR (€)	Mar. 31, 2014 Forward Contracts GBP (£)	Dec. 31, 2013 Forward Contracts EUR (€)	Dec. 31, 2013 Forward Contracts GBP (£)
Derivatives, Fair Value [Line Items]
Derivative, number of instruments held	2		2
Derivative, notional amount						€ 4,700,000	£ 1,800,000	€ 6,300,000	£ 2,000,000
Foreign currency contract, asset, fair value disclosure	0		0
Derivative Instruments Not Designated as Hedging Instruments, Loss				(200,000)	(100,000)
Foreign Currency Transaction Gain, before Tax	100,000
Foreign Currency Transaction Loss, before tax		$ (200,000)