Fair Value of Financial Instruments - Derivatives (Details)	3 Months Ended		9 Months Ended			3 Months Ended		9 Months Ended
	Sep. 30, 2014 USD ($)	Sep. 30, 2013 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2013 USD ($)	Dec. 31, 2013 USD ($)	Sep. 30, 2014 Forward Contracts USD ($)	Sep. 30, 2013 Forward Contracts USD ($)	Sep. 30, 2014 Forward Contracts USD ($)	Sep. 30, 2013 Forward Contracts USD ($)	Sep. 30, 2014 Forward Contracts EUR (€) contract	Sep. 30, 2014 Forward Contracts GBP (£)	Dec. 31, 2013 Forward Contracts EUR (€) contract	Dec. 31, 2013 Forward Contracts GBP (£)
Derivatives, Fair Value [Line Items]
Derivative, number of instruments held										2	2	2	2
Derivative, notional amount										€ 4,100,000	£ 2,100,000	€ 6,300,000	£ 2,000,000
Foreign currency contract, asset, fair value disclosure	0		0		0
Derivative instruments not designated as hedging instruments, gain						500,000		400,000
Foreign currency transaction loss	600,000		600,000
Derivative instruments not designated as hedging instruments, loss							400,000		600,000
Foreign currency transaction gain		$ 300,000		$ 100,000