Income Taxes (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]
Income tax provision as percentage of income before taxes	19.10%		12.20%
Income tax provision, foreign filing	$ 424,000
Benefit for 2012 research tax credits			1,400,000
Percentage of income before taxes		33.40%		33.50%
Tax benefits recognized due to settlements with taxing authorities		176,000		176,000
Liability for uncertain tax positions	12,400,000		12,400,000
Net liability, reduced for the federal effects of potential state tax exposures	9,000,000		9,000,000
Tax provision, included not yet reduced income tax payments	5,300,000		5,300,000
Anticipated significant change to uncertain income tax positions accrued in current and long term taxes payable	3,700,000		3,700,000
Long-term uncertain income tax positions within the next 12 months	3,425,000		3,425,000		2,759,000
Accrued Income Taxes, Current	274,000		274,000
Interest and penalties related to income tax	435,000		435,000			354,000
Current deferred tax assets	21,800,000		21,800,000
Net long-term deferred tax assets	133,000		133,000
Deferred tax valuation allowance	$ 8,200,000		$ 8,200,000