Income Taxes - Unrecognized Tax Benefit Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of year	$ 8,152	$ 7,838	$ 8,306
Additions based on tax positions related to current year	459	368	346
Additions to tax provision of prior years	0	0	0
Reductions to tax provision of prior years	(45)	(54)	(814)
Lapse of the applicable statute of limitations	0	0	0
Balance at end of year	8,566	$ 8,152	$ 7,838
Federal
Net Operating Losses and Tax Credit Carryforwards
Net operating losses, amount	213,061
Tax credits, amount	5,634
State
Net Operating Losses and Tax Credit Carryforwards
Net operating losses, amount	120,234
Tax credits, amount	7,048
Foreign
Net Operating Losses and Tax Credit Carryforwards
Net operating losses, amount	627
Tax credits, amount	$ 10