Income Taxes (Details 3) (USD $)	12 Months Ended
	Dec. 31, 2012 item	Dec. 31, 2011	Dec. 31, 2010
Activity relating to the Company's unrecognized tax benefits
Balance at the beginning of the period	$ 11,144,000	$ 9,501,000	$ 7,467,000
Gross increases related to tax positions in prior period	(12,000)		(431,000)
Gross increases related to tax positions in prior period		(185,000)
Gross increases related to current period tax positions	992,000	1,828,000	1,603,000
Balance at the end of the period	12,148,000	11,144,000	9,501,000
Portion of unrecognized tax benefits, if recognized would decrease the entity's tax provision and increase net income	9,900,000
Number of states in which accrued a nominal amount of interest and penalties for specific exposures	2
Research credits | Federal
Tax credit Carryforward
Credits subject to expiration between 2022 and 2031	17,400,000
Research credits | California
Tax credit Carryforward
Credits not subject to expiration	20,700,000
Enterprise zone credits | California
Tax credit Carryforward
Credits not subject to expiration	$ 7,000,000