Income Taxes	9 Months Ended
Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Income tax expense for the three and nine months ended September 30, 2017 was $118.2 million and $355.9 million, representing an effective tax rate of 28.4% and 29.7%, respectively. The provision for income taxes includes Federal and State research tax credits of $17.6 million recognized in the three months ended September 30, 2017 due to the completion of a recent study of the Corporation’s technology spend between 2013 and 2016, partially offset by $4.3 million related to an increase in the Illinois state deferred income tax reserve resulting from an increase in the Illinois income tax rate. The prior-year three- and nine- month provision for income taxes was $116.1 million and $361.6 million, representing an effective tax rate of 31.1% and 32.1%, respectively.

Income Taxes

9 Months Ended

Sep. 30, 2017

Income tax expense for the three and nine months ended September 30, 2017 was $118.2 million and $355.9 million, representing an effective tax rate of 28.4% and 29.7%, respectively. The provision for income taxes includes Federal and State research tax credits of $17.6 million recognized in the three months ended September 30, 2017 due to the completion of a recent study of the Corporation’s technology spend between 2013 and 2016, partially offset by $4.3 million related to an increase in the Illinois state deferred income tax reserve resulting from an increase in the Illinois income tax rate.

The prior-year three- and nine- month provision for income taxes was $116.1 million and $361.6 million, representing an effective tax rate of 31.1% and 32.1%, respectively.