Income Taxes:

3 Months Ended

Mar. 31, 2020

Income Tax Disclosure [Abstract]

Income Tax Disclosure [Text Block]

Income Taxes

Income taxes were accrued at an estimated effective tax rate of 17% and 7% for the three months ended March 31, 2020 and 2019, respectively.

The effective tax rate for the three months ended March 31, 2020 differs from the federal statutory rate of 21% principally because of the effect of the mix of U.S. and foreign incomes, state income taxes, global intangible low-taxed income ("GILTI"), foreign-derived intangible income ("FDII") and tax credits.

The effective tax rate for the three months ended March 31, 2019 differs from the federal statutory rate of 21% principally because of the effect of the mix of U.S. and foreign incomes, state income taxes, GILTI and tax credits. The effective tax rate during the three months ended March 31, 2019 included a discrete tax benefit of $5.6 million related to the excess tax benefits recognized on stock option exercises and the vesting of restricted stock units during the period. In addition, the effective tax rate during the three months ended March 31, 2019 included a discrete tax provision of $1.8 million as a result of a revaluation of the contingent consideration.