The Company determines its periodic income tax provision based upon the current period income and the annual estimated tax rate for the Company adjusted for discrete items including tax credits and changes to prior year estimates. The estimated tax rate is revised, if necessary, as of the end of each successive interim period during the fiscal year to the Company's current annual estimated tax rate.

Income tax provision for the first quarter of 2017 reflects an effective tax rate of 24.3 percent, compared to an effective tax rate of 31.7 percent for the comparable period in the prior year. The effective rate in both periods includes the effect of beneficial permanent differences including tax-exempt interest income and a favorable U.S. manufacturing deduction. The Company adopted the provisions of ASU 2016-09 in the first quarter of 2017 that requires excess tax benefits and deficiencies to be recognized as a component of income tax expense rather than equity. This resulted in a beneficial discrete adjustment of $580 thousand to the provision for income taxes in the first quarter of 2017. The first quarter 2016 effective tax rate reflects certain beneficial permanent tax differences generated from life insurance proceeds.