Income Taxes	9 Months Ended
Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Income tax expense for the three months ended September 30, 2018 and September 30, 2017 was $106.5 million and $118.2 million, representing an effective tax rate of 22.1% and 28.4%, respectively. For the three months ended September 30, 2018, the provision for income taxes includes adjustments of $5.5 million associated with the re-establishment of a deferred tax asset based on the issuance of guidance by the IRS related to the implementation of the TCJA. For the three months ended September 30, 2017, the provision for income taxes includes Federal and State research tax credits of $17.6 million due to the completion of a study of the Corporation’s technology spend between 2013 and 2016. Income tax expense for the nine months ended September 30, 2018 and September 30, 2017 was $325.4 million and $355.9 million, representing an effective tax rate of 22.1% and 29.7%, respectively. For the nine months ended September 30, 2018, the provision for income taxes includes a $22.6 million benefit resulting from a change in accounting method regarding the timing of tax deductions for software development-related expenses, partially offset by a $10.3 million net provision representing adjustments to the initial estimated impact of the TCJA recorded in the fourth quarter of 2017.

Income Taxes

Income tax expense for the three months ended September 30, 2018 and September 30, 2017 was $106.5 million and $118.2 million, representing an effective tax rate of 22.1% and 28.4%, respectively. For the three months ended September 30, 2018, the provision for income taxes includes adjustments of $5.5 million associated with the re-establishment of a deferred tax asset based on the issuance of guidance by the IRS related to the implementation of the TCJA. For the three months ended September 30, 2017, the provision for income taxes includes Federal and State research tax credits of $17.6 million due to the completion of a study of the Corporation’s technology spend between 2013 and 2016.

Income tax expense for the nine months ended September 30, 2018 and September 30, 2017 was $325.4 million and $355.9 million, representing an effective tax rate of 22.1% and 29.7%, respectively. For the nine months ended September 30, 2018, the provision for income taxes includes a $22.6 million benefit resulting from a change in accounting method regarding the timing of tax deductions for software development-related expenses, partially offset by a $10.3 million net provision representing adjustments to the initial estimated impact of the TCJA recorded in the fourth quarter of 2017.