Income Taxes (Details 3) (USD $)	12 Months Ended
	Dec. 31, 2011 state	Dec. 31, 2010	Dec. 31, 2009
Activity relating to the Company's unrecognized tax benefits
Balance at the beginning of the period	$ 9,501,000	$ 7,467,000	$ 6,904,000
Gross increases related to tax positions in prior period		431,000
Gross decreases related to tax positions in prior period	(185,000)
Gross increases related to current period tax positions	1,828,000	1,603,000	563,000
Balance at the end of the period	11,144,000	9,501,000	7,467,000
Portion of unrecognized tax benefits, if recognized would decrease the entity's tax provision and increase net income	9,200,000
Number of states in which accrued a nominal amount of interset and penalties for specific exposures	2
Research credits | Federal
Tax credit Carryforward
Credits subject to expiration between 2012 and 2030	24,900,000
Research credits | California
Tax credit Carryforward
Credits not subject to expiration	18,100,000
Enterprise zone credits | California
Tax credit Carryforward
Credits not subject to expiration	$ 6,700,000