Stockholders' Equity and Employee Stock Option Plans Stock option outstanding by exercise price range (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options and SARS Outstanding, Weighted Average Remaining Contractual Term	5 years 3 months 15 days
Options and SARS, Outstanding, Weighted Average Exercise Price	$ 6.08	$ 8.71	$ 8.55	$ 8.45
Options and SARS, Outstanding, Number	3,939,315	3,103,472	4,275,648	5,928,776
Options, Vested and Expected to Vest, Outstanding, Number	3,778,267
Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term	5 years 3 months 12 days
Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price	$ 6.18
Options, Exercisable, Number	1,696,476
Options, Exercisable, Weighted Average Remaining Contractual Term	1 year 7 months 18 days
Options, Exercisable, Weighted Average Exercise Price	$ 8.54
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	$ 2.51
Exercise Price Range, Upper Range Limit	$ 2.57
Exercise Price Range, Number of Outstanding Options and SARS	11,400
Options and SARS Outstanding, Weighted Average Remaining Contractual Term	9 years 10 months 18 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 2.57
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	$ 3.17
Exercise Price Range, Upper Range Limit	$ 3.17
Exercise Price Range, Number of Outstanding Options and SARS	1,662,084
Options and SARS Outstanding, Weighted Average Remaining Contractual Term	9 years 4 months 22 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 3.17
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	$ 3.40
Exercise Price Range, Upper Range Limit	$ 7.46
Exercise Price Range, Number of Outstanding Options and SARS	601,775
Options and SARS Outstanding, Weighted Average Remaining Contractual Term	4 years 8 months 24 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 5.97
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	$ 7.47
Exercise Price Range, Upper Range Limit	$ 7.47
Exercise Price Range, Number of Outstanding Options and SARS	499,059
Options and SARS Outstanding, Weighted Average Remaining Contractual Term	1 year 4 months 15 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 7.47
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	$ 7.69
Exercise Price Range, Upper Range Limit	$ 7.69
Exercise Price Range, Number of Outstanding Options and SARS	414,401
Options and SARS Outstanding, Weighted Average Remaining Contractual Term	0 years 11 months 17 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 7.69
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	$ 7.89
Exercise Price Range, Upper Range Limit	$ 10.62
Exercise Price Range, Number of Outstanding Options and SARS	454,450
Options and SARS Outstanding, Weighted Average Remaining Contractual Term	2 years 0 months 11 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 9.43
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	$ 11.33
Exercise Price Range, Upper Range Limit	$ 13.32
Exercise Price Range, Number of Outstanding Options and SARS	279,396
Options and SARS Outstanding, Weighted Average Remaining Contractual Term	0 years 11 months 9 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 12.79
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	$ 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	1 year 9 months 12 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 13.85
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	$ 15.45
Exercise Price Range, Upper Range Limit	$ 15.45
Exercise Price Range, Number of Outstanding Options and SARS	1,000
Options and SARS Outstanding, Weighted Average Remaining Contractual Term	0 years 3 months 8 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 15.45
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	$ 18.55
Exercise Price Range, Upper Range Limit	$ 18.55
Exercise Price Range, Number of Outstanding Options and SARS	9,000
Options and SARS Outstanding, Weighted Average Remaining Contractual Term	0 years 0 months 11 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 18.55