Income Taxes	6 Months Ended
Jun. 30, 2017
Income Tax Disclosure [Abstract]
Income Taxes	13. Income Taxes The Company’s effective income tax rate for the three months ended June 30, 2017 was 37.9%, compared with 36.3% for the three months ended June 30, 2016. For the six months ended June 30, 2017, the effective income tax rate was 37.5%, compared to 35.1% for the six months ended June 30, 2016. The effective income tax rate fluctuates from the U.S. statutory tax rate based on, among other factors, changes in pretax income in countries with varying statutory tax rates, impact of state and local taxes, and other differences related to the recognition of income and expense between U.S. GAAP and tax. Compared with the second quarter of 2016, the higher effective tax rate for the second quarter of 2017 was primarily related to the impact of share-based payment transactions and non-deductible transaction costs associated with the SSE merger. Compared with the first six months of 2016, the higher effective tax rate for the first six months of 2017 was primarily attributable to the changes in state and local taxes, share-based payment transactions, and non-deductible transaction costs associated with the SSE merger, as well as true-up adjustments of Canadian taxes for tax return filings during the six months ended June 30, 2017. The difference also reflects the impact from lost benefits of previous IRC section 199 deductions due to net operating loss carrybacks filed during the six months ended June 30, 2016.

13. Income Taxes

The Company’s effective income tax rate for the three months ended June 30, 2017 was 37.9%, compared with 36.3% for the three months ended June 30, 2016. For the six months ended June 30, 2017, the effective income tax rate was 37.5%, compared to 35.1% for the six months ended June 30, 2016. The effective income tax rate fluctuates from the U.S. statutory tax rate based on, among other factors, changes in pretax income in countries with varying statutory tax rates, impact of state and local taxes, and other differences related to the recognition of income and expense between U.S. GAAP and tax.

Compared with the second quarter of 2016, the higher effective tax rate for the second quarter of 2017 was primarily related to the impact of share-based payment transactions and non-deductible transaction costs associated with the SSE merger. Compared with the first six months of 2016, the higher effective tax rate for the first six months of 2017 was primarily attributable to the changes in state and local taxes, share-based payment transactions, and non-deductible transaction costs associated with the SSE merger, as well as true-up adjustments of Canadian taxes for tax return filings during the six months ended June 30, 2017. The difference also reflects the impact from lost benefits of previous IRC section 199 deductions due to net operating loss carrybacks filed during the six months ended June 30, 2016.