Income Taxes	9 Months Ended
Sep. 30, 2011
Income Taxes [Abstract]
Income Taxes	Income Taxes The Company’s effective income tax rate, including discrete items, was 35.7% and 37.0% for the nine months ended September 30, 2011 and 2010, respectively. The effective income tax rate is based upon estimated income for the year, the estimated composition of the income in different jurisdictions and discrete adjustments, if any, in the applicable quarterly periods including settlements of tax audits or assessments, the resolution or identification of tax position uncertainties, and acquisitions of other companies. The discrete items also include the tax effect of disqualifying dispositions of incentive stock options and shares purchased under the Company's Employee Stock Purchase Plan. For each of the nine months ended September 30, 2011 and September 30, 2010, the effective income tax rate was higher than the federal statutory tax rate mainly due to the effects of accounting for stock-based compensation in accordance with the authoritative guidance for share-based payments, and state income tax expense.

Income Taxes

9 Months Ended

Sep. 30, 2011

The Company’s effective income tax rate, including discrete items, was 35.7% and 37.0% for the nine months ended September 30, 2011 and 2010, respectively. The effective income tax rate is based upon estimated income for the year, the estimated composition of the income in different jurisdictions and discrete adjustments, if any, in the applicable quarterly periods including settlements of tax audits or assessments, the resolution or identification of tax position uncertainties, and acquisitions of other companies. The discrete items also include the tax effect of disqualifying dispositions of incentive stock options and shares purchased under the Company's Employee Stock Purchase Plan. For each of the nine months ended September 30, 2011 and September 30, 2010, the effective income tax rate was higher than the federal statutory tax rate mainly due to the effects of accounting for stock-based compensation in accordance with the authoritative guidance for share-based payments, and state income tax expense.