Income Taxes	6 Months Ended
Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Income tax expense for the three months ended June 30, 2018 and June 30, 2017 was $116.8 million and $122.9 million, representing an effective tax rate of 23.0% and 31.4%, respectively. Income tax expense for the six months ended June 30, 2018 and June 30, 2017 was $218.9 million and $237.7 million, representing an effective tax rate of 22.1% and 30.4%, respectively. For the six months ended June 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 $15.8 million net provision recorded in the first quarter of 2018 representing adjustments to the initial estimated impact of the TCJA recorded in the fourth quarter of 2017.

Income Taxes

6 Months Ended

Jun. 30, 2018

Income tax expense for the three months ended June 30, 2018 and June 30, 2017 was $116.8 million and $122.9 million, representing an effective tax rate of 23.0% and 31.4%, respectively.

Income tax expense for the six months ended June 30, 2018 and June 30, 2017 was $218.9 million and $237.7 million, representing an effective tax rate of 22.1% and 30.4%, respectively. For the six months ended June 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 $15.8 million net provision recorded in the first quarter of 2018 representing adjustments to the initial estimated impact of the TCJA recorded in the fourth quarter of 2017.