Income taxes	6 Months Ended
Jun. 30, 2017
Income taxes
Income taxes	Note 5. Income taxes For the six months ended June 30, 2017 and 2016, our income tax expense has been computed utilizing the estimated annual effective rates of 35.9% and 35.8%, respectively. The difference between the annual effective rate of 35.9% and the statutory Federal income tax rate of 35% in the six months ended June 30, 2017, is driven by foreign withholding taxes and foreign permanent differences, which were offset by foreign tax credits. The difference between the annual effective rate of 35.8% and the statutory Federal income tax rate of 35% in the six month period ended June 30, 2016, is primarily due to state and foreign income taxes. Income tax expense for the three and six months ended June 30, 2017, was $2.8 million and $4.5 million, respectively. Income tax expense for the three and six months ended June 30, 2016, was $2.8 million and $4.3 million, respectively.

Income taxes

6 Months Ended

Jun. 30, 2017

Note 5. Income taxes

For the six months ended June 30, 2017 and 2016, our income tax expense has been computed utilizing the estimated annual effective rates of 35.9% and 35.8%, respectively. The difference between the annual effective rate of 35.9% and the statutory Federal income tax rate of 35% in the six months ended June 30, 2017, is driven by foreign withholding taxes and foreign permanent differences, which were offset by foreign tax credits. The difference between the annual effective rate of 35.8% and the statutory Federal income tax rate of 35% in the six month period ended June 30, 2016, is primarily due to state and foreign income taxes.

Income tax expense for the three and six months ended June 30, 2017, was $2.8 million and $4.5 million, respectively. Income tax expense for the three and six months ended June 30, 2016, was $2.8 million and $4.3 million, respectively.