Income Taxes Income Taxes (Schedule of Difference Between Effective and Statutory) (Details)	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Tax Disclosure [Abstract]
United States federal income tax rate	35.00%	35.00%	35.00%
State taxes	3.50%	2.80%	2.90%
Nondeductible stock-based compensation	1.30%	0.80%	0.10%
United States federal and state research and development credits	(0.60%)	(2.40%)	(2.60%)
Change in state tax rates	(0.40%)	(0.10%)	0.50%
Foreign earnings	(3.50%)	(2.20%)	(0.40%)
Expiration of capital loss carryforward	0.00%	2.10%	0.00%
Disallowed officer compensation	0.60%	0.00%	0.00%
Other	0.70%	0.90%	(1.00%)
Change in the deferred tax asset valuation allowance	0.00%	(2.30%)	0.20%
Effective Income Tax Rate, Continuing Operations	36.60%	34.60%	34.70%

Effective Income Tax Rate Reconciliation, Disallowed Officer Compensation

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Effective Income Tax Rate Reconciliation, Expiration of Capital Loss Carryforward

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- Definition

A ratio calculated by dividing the reported amount of income tax expense attributable to continuing operations for the period by GAAP-basis pretax income from continuing operations.

+ References

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The domestic federal statutory tax rate applicable under enacted tax laws to the Company's pretax income from continuing operations for the period. The "statutory" tax rate is the regular tax rate if there are alternative tax systems.

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to changes in the valuation allowance for deferred tax assets.

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The portion of the difference between total income tax expense or benefit as reported in the Income Statement and the expected income tax expense or benefit that is attributable to changes in the income tax laws or rates.

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate that can be explained by the difference between statutory income tax rates in foreign jurisdictions and the domestic federal statutory income tax rate recorded during the period.

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to differences in the deductibility or nondeductibility of incentive stock options and other equity-based compensation costs in accordance with generally accepted accounting principles and enacted tax laws.

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to all other items not otherwise listed in the existing taxonomy.

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to changes in state and local income tax contingencies, whether recorded or adjusted, during the period.

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate that can be explained by research tax credits generated or utilized under enacted tax laws during the period.

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