Stockholders' Equity and Employee Stock Option Plans Stock option outstanding by exercise price range (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options and SARS Outstanding, Weighted Average Remaining Contractual Term	7 years 0 months 29 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	$ 4,640
Options and SARS, Outstanding, Weighted Average Exercise Price	$ 4.13		$ 6.08	$ 8.71	$ 8.55
Options and SARS, Outstanding, Number	4,104,849	5,505,404	3,939,315	3,103,472	4,275,648
Options, Vested and Expected to Vest, Outstanding, Number	3,918,854
Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term	7 years 0 months 21 days
Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price	$ 4.20
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value	4,212
Options, Exercisable, Number	1,348,270
Options, Exercisable, Weighted Average Remaining Contractual Term	3 years 7 months 20 days
Options, Exercisable, Weighted Average Exercise Price	$ 6.60
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value	0
Exercise Price Range One [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	$ 2.11
Exercise Price Range, Upper Range Limit	$ 2.29
Exercise Price Range, Number of Outstanding Options and SARS	419,600
Options and SARS Outstanding, Weighted Average Remaining Contractual Term	9 years 8 months 4 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 2.19
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	4,640
Exercise Price Range Two [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	$ 2.37
Exercise Price Range, Upper Range Limit	$ 2.37
Exercise Price Range, Number of Outstanding Options and SARS	1,183,829
Options and SARS Outstanding, Weighted Average Remaining Contractual Term	9 years 5 months 8 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 2.37
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	0
Exercise Price Range Three [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	$ 2.51
Exercise Price Range, Upper Range Limit	$ 2.57
Exercise Price Range, Number of Outstanding Options and SARS	92,500
Options and SARS Outstanding, Weighted Average Remaining Contractual Term	9 years 3 months 18 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 2.55
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	0
Exercise Price Range Four [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	$ 3.17
Exercise Price Range, Upper Range Limit	$ 3.17
Exercise Price Range, Number of Outstanding Options and SARS	1,217,567
Options and SARS Outstanding, Weighted Average Remaining Contractual Term	8 years 4 months 13 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 3.17
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	0
Exercise Price Range Five [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	$ 3.40
Exercise Price Range, Upper Range Limit	$ 7.46
Exercise Price Range, Number of Outstanding Options and SARS	513,725
Options and SARS Outstanding, Weighted Average Remaining Contractual Term	4 years 2 months 23 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 6.02
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	0
Exercise Price Range Six [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	$ 7.47
Exercise Price Range, Upper Range Limit	$ 8.20
Exercise Price Range, Number of Outstanding Options and SARS	431,978
Options and SARS Outstanding, Weighted Average Remaining Contractual Term	0 years 5 months 19 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 7.55
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	0
Exercise Price Range Seven [Member] [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	$ 9.08
Exercise Price Range, Upper Range Limit	$ 10.62
Exercise Price Range, Number of Outstanding Options and SARS	123,900
Options and SARS Outstanding, Weighted Average Remaining Contractual Term	2 years 4 months 9 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 9.99
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	0
Exercise Price Range Eight [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	$ 12.11
Exercise Price Range, Upper Range Limit	$ 12.11
Exercise Price Range, Number of Outstanding Options and SARS	40,000
Options and SARS Outstanding, Weighted Average Remaining Contractual Term	0 years 8 months 8 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 12.11
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	0
Exercise Price Range Nine [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	$ 12.82
Exercise Price Range, Upper Range Limit	$ 12.82
Exercise Price Range, Number of Outstanding Options and SARS	75,000
Options and SARS Outstanding, Weighted Average Remaining Contractual Term	0 years 10 months 9 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 12.82
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	0
Exercise Price Range Ten [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	$ 13.85
Exercise Price Range, Upper Range Limit	$ 13.85
Exercise Price Range, Number of Outstanding Options and SARS	6,750
Options and SARS Outstanding, Weighted Average Remaining Contractual Term	0 years 9 months 10 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 13.85
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	$ 0