Equity Award Plans - Stock Options (Details) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Number of Options
Ending balances (in shares)	3,655	4,684
Stock Options [Member]
Number of Options
Beginning balances (in shares)	4,684	6,247	5,918
Granted	1,992	527	1,629
Forfeited, canceled or expired	2,534	1,006	636
Exercised	487	1,084	664
Ending balances (in shares)	3,655	4,684	6,247	5,918
Options vested and expected to vest (in shares)	3,184	4,524	5,957
Options exercisable (in shares)	1,752	3,328	3,348
Weighted Average Exercise Price
Beginning balance (per share)	$ 10.85	$ 9.44	$ 7.89
Granted	$ 8.72	$ 15.08	$ 13.39
Forfeited, canceled or expired	$ 12.06	$ 12.53	$ 10.73
Exercised	$ 3.51	$ 3.22	$ 4.04
Ending balance (per share)	$ 9.82	$ 10.85	$ 9.44	$ 7.89
Options vested and expected to vest (per share)	$ 9.95	$ 10.73	$ 9.27
Options exercisable (per share)	$ 10.44	$ 9.83	$ 6.82
Weighted Average Contractual Term (Years)
Beginning balance, in years	7 years 6 months 11 days	5 years 3 months 26 days	7 years 2 months 23 days	7 years 3 months 4 days
Ending balance, in years	7 years 6 months 11 days	5 years 3 months 26 days	7 years 2 months 23 days	7 years 3 months 4 days
Options vested and expected to vest (in years)	7 years 3 months 4 days	5 years 2 months 9 days	7 years 1 month 13 days
Options exercisable (in years)	5 years 9 months 22 days	3 years 11 months 12 days	5 years 8 months 1 day
Aggregate Intrinsic Value
Beginning balance	$ 4,318,000	$ 28,424,000	$ 18,790,000
Ending balance	3,059,000	4,318,000	28,424,000	18,790,000
Options vested and expected to vest	2,862,000	4,318,000	28,141,000
Options exercisable	2,257,000	4,317,000	24,007,000
Intrinsic value of options exercised during period	$ 2,600,000	$ 9,200,000	$ 7,900,000
Weighted average grant date fair value (per share)	$ 4.07	$ 6.96	$ 5.96