Commitments and Contingencies - Government Grants (Details) (USD $)	12 Months Ended
	Dec. 31, 2014 agreement employee	Dec. 31, 2013	Dec. 31, 2012
Gain Contingencies [Line Items]
Government training reimbursement number of agreements	3
Government training reimbursement number of employees	378
Proceeds from government for training reimbursement	$ 194,000	$ 1,520,000	$ 357,000
Gain (loss) on government grant reimbursement	99,000	0	0
Deferred government grant obligation, current	2,324,000	100,000
Other Operating Income (Expense)
Gain Contingencies [Line Items]
Gain (loss) on government grant reimbursement	99,000	0	0
Training Reimbursement
Gain Contingencies [Line Items]
Deferred government grant obligation	3,500,000	3,400,000
Deferred government grant obligation, current	$ 697,000	$ 100,000