Income Taxes	6 Months Ended
Jun. 30, 2011
Income Taxes [Abstract]
INCOME TAXES	2. INCOME TAXES Our effective tax rate decreased from 34.6% in the six months ended June 30, 2010 to 32.5% in the six months ended June 30, 2011. The decrease is primarily attributable to the research tax credit and increased tax benefits from a higher volume of stock option exercises during the six months ended June 30, 2011. The inclusion of the benefit for the research tax credit in the six months ended June 30, 2011 resulted in a 2.2 percentage point decrease in our tax rate. In addition, increased benefits from a higher volume of stock option exercises during the six months ended June 30, 2011 resulted in a 1.6 percentage point decrease in our tax rate. The tax provision rate in 2010 was affected by a benefit related to the completion of an audit for the years 2006 and 2007 by the Internal Revenue Service and a larger manufacturer's deduction. The completion of the audit provided a 1.0 percentage point benefit during the six months ended June 30, 2010. The higher manufacturer's deduction resulted in a 0.7 percentage point benefit in our effective tax rate for the six months ended June 30, 2010. Also, the tax provision rate in the first six months of 2010 did not include the benefit of the research tax credit, which expired on December 31, 2009. The credit was reinstated during the fourth quarter of 2010.

Income Taxes

6 Months Ended

Jun. 30, 2011

2. INCOME TAXES

Our effective tax rate decreased from 34.6% in the six months ended June 30, 2010 to 32.5% in the six months ended June 30, 2011. The decrease is primarily attributable to the research tax credit and increased tax benefits from a higher volume of stock option exercises during the six months ended June 30, 2011. The inclusion of the benefit for the research tax credit in the six months ended June 30, 2011 resulted in a 2.2 percentage point decrease in our tax rate. In addition, increased benefits from a higher volume of stock option exercises during the six months ended June 30, 2011 resulted in a 1.6 percentage point decrease in our tax rate.

The tax provision rate in 2010 was affected by a benefit related to the completion of an audit for the years 2006 and 2007 by the Internal Revenue Service and a larger manufacturer's deduction. The completion of the audit provided a 1.0 percentage point benefit during the six months ended June 30, 2010. The higher manufacturer's deduction resulted in a 0.7 percentage point benefit in our effective tax rate for the six months ended June 30, 2010. Also, the tax provision rate in the first six months of 2010 did not include the benefit of the research tax credit, which expired on December 31, 2009. The credit was reinstated during the fourth quarter of 2010.