17.	INCOME TAXES

Our effective income tax rates for the three and nine months ended September 30, 2015 were 4.1 percent and 3.7 percent, respectively, compared to 17.0 percent and 16.8 percent, respectively, for the three and nine months ended September 30, 2014. The effective income tax rates were determined using the estimated annual effective tax rate after considering discrete income tax items for each respective period. The effective income tax rates for the three and nine months ended September 30, 2015 were lower than the United States statutory federal income tax rate primarily due to the unfavorable permanent difference for the preliminary goodwill impairment charge during the three and nine months ended September 30, 2015 that is not deductible for income tax purposes. The effective income tax rates for the three and nine month periods ended September 30, 2014 were lower than the United States statutory federal income tax rate primarily due to various permanent differences, including deductions for manufacturing as well as the favorable impact of changes in uncertain tax positions of $4.5 million and $8.0 million for the three and nine month periods ended September 30, 2014, respectively.