Stockholders' Equity and Employee Stock Option Plans Stock option outstanding by exercise price range (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Mar. 31, 2013
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options and SARS Outstanding, Weighted Average Remaining Contractual Term	8 years 2 months 5 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	$ 4
Options and SARS, Outstanding, Weighted Average Exercise Price	$ 13.94	$ 24.72	$ 34.00	$ 41.30
Options and SARS, Outstanding, Number	505,872	285,536	259,679	410,484	550,540
Options, Vested and Expected to Vest, Outstanding, Number	483,234
Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term	8 years 2 months 5 days
Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price	$ 14.29
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value	$ 4
Options, Exercisable, Number	200,830
Options, Exercisable, Weighted Average Remaining Contractual Term	6 years 5 months 12 days
Options, Exercisable, Weighted Average Exercise Price	$ 24.70
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value	$ 3,800
$4.51-$4.73
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	$ 4.51
Exercise Price Range, Upper Range Limit	$ 4.73
Exercise Price Range, Number of Outstanding Options and SARS	80,000
Options and SARS Outstanding, Weighted Average Remaining Contractual Term	9 years 4 months 13 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 4.68
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	$ 4
5.22
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	$ 5.22
Exercise Price Range, Upper Range Limit	$ 5.22
Exercise Price Range, Number of Outstanding Options and SARS	187,000
Options and SARS Outstanding, Weighted Average Remaining Contractual Term	9 years 8 months 27 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 5.22
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	$ 0
5.45-9.11
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	$ 5.45
Exercise Price Range, Upper Range Limit	$ 9.11
Exercise Price Range, Number of Outstanding Options and SARS	87,750
Options and SARS Outstanding, Weighted Average Remaining Contractual Term	8 years 6 months
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 8.70
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	$ 0
9.15-23.70
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	$ 9.15
Exercise Price Range, Upper Range Limit	$ 23.7
Exercise Price Range, Number of Outstanding Options and SARS	84,490
Options and SARS Outstanding, Weighted Average Remaining Contractual Term	7 years 22 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 21.26
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	$ 0
24.20-35.20
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	$ 24.20
Exercise Price Range, Upper Range Limit	$ 35.20
Exercise Price Range, Number of Outstanding Options and SARS	41,632
Options and SARS Outstanding, Weighted Average Remaining Contractual Term	5 years 11 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 30.72
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	$ 0
$74.60
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	$ 74.6
Exercise Price Range, Upper Range Limit	$ 74.6
Exercise Price Range, Number of Outstanding Options and SARS	25,000
Options and SARS Outstanding, Weighted Average Remaining Contractual Term	7 months 17 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 74.60
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	$ 0