Income Taxes	9 Months Ended
Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	NOTE H - Income Taxes The effective tax rate for the third quarter of 2018 was 18.5% compared to 30.8% in the third quarter of 2017. The effective tax rate for the first nine months of 2018 was 21.4% compared to 30.8% in the same period of 2017. The difference in 2018 tax rates compared to 2017 was primarily due to the U.S. federal income tax legislation enacted on December 22, 2017, which lowered the U.S. statutory income tax rate from 35.0% to 21.0%. In addition, in the third quarter of 2018, the tax rate decreased 3.1% due to a one-time reduction in tax liability related to extended warranty contracts and higher realized R&D tax credits.

Income Taxes

9 Months Ended

Sep. 30, 2018

NOTE H - Income Taxes

The effective tax rate for the third quarter of 2018 was 18.5% compared to 30.8% in the third quarter of 2017. The effective tax rate for the first nine months of 2018 was 21.4% compared to 30.8% in the same period of 2017. The difference in 2018 tax rates compared to 2017 was primarily due to the U.S. federal income tax legislation enacted on December 22, 2017, which lowered the U.S. statutory income tax rate from 35.0% to 21.0%. In addition, in the third quarter of 2018, the tax rate decreased 3.1% due to a one-time reduction in tax liability related to extended warranty contracts and higher realized R&D tax credits.