Commitments and Contingencies - Narrative (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Other Commitments [Line Items]
Operating leases, rent expense	$ 2,900,000	$ 2,400,000	$ 1,900,000
Government grants	858,000	974,000
France [Member]
Other Commitments [Line Items]
Government grants	$ 858,000	$ 974,000