Income Taxes	6 Months Ended
Jun. 30, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Income tax expense was $55 million for the three months ended June 30, 2017, compared to $70 million for the same period of the prior year. The effective income tax rate, expressed by calculating the income tax expense as a percentage of Income before income taxes, was 27.9% for the three months ended June 30, 2017 and differed from the US federal statutory rate primarily due to $19 million of excess tax benefits on equity compensation. The effective tax rate for the same period of the prior year was 37.3% and differed from the US federal statutory rate primarily due to state and local income taxes. Income tax expense was $71 million for the six months ended June 30, 2017, compared to $116 million for the same period of the prior year. The effective income tax rate, expressed by calculating the income tax expense as a percentage of Income before income taxes, was 26.2% for the six months ended June 30, 2017 and differed from the US federal statutory rate primarily due to $30 million of excess tax benefits on equity compensation. The effective tax rate for the same period of the prior year was 37.3% and differed from the US federal statutory rate primarily due to state and local income taxes.

Income Taxes

6 Months Ended

Jun. 30, 2017

Income tax expense was $55 million for the three months ended June 30, 2017, compared to $70 million for the same period of the prior year. The effective income tax rate, expressed by calculating the income tax expense as a percentage of Income before income taxes, was 27.9% for the three months ended June 30, 2017 and differed from the US federal statutory rate primarily due to $19 million of excess tax benefits on equity compensation. The effective tax rate for the same period of the prior year was 37.3% and differed from the US federal statutory rate primarily due to state and local income taxes.

Income tax expense was $71 million for the six months ended June 30, 2017, compared to $116 million for the same period of the prior year. The effective income tax rate, expressed by calculating the income tax expense as a percentage of Income before income taxes, was 26.2% for the six months ended June 30, 2017 and differed from the US federal statutory rate primarily due to $30 million of excess tax benefits on equity compensation. The effective tax rate for the same period of the prior year was 37.3% and differed from the US federal statutory rate primarily due to state and local income taxes.