Income Taxes

The following table provides details of income taxes (in millions, except percentages):



	Three Months Ended June 30,						Six Months Ended June 30,
	2017			2016			2017			2016
Income before income taxes	$	245.2		$	192.2		$	385.8		$	318.7
Income tax provision	$	65.4		$	52.2		$	97.2		$	87.3
Effective tax rate	26.7		%	27.2		%	25.2		%	27.4		%

The Company's effective tax rates during the three and six months ended June 30, 2017 and June 30, 2016, differ from the statutory rate primarily due to the benefit of the Section 199 deduction for U.S. production activities, the federal research and development credit, and earnings in foreign jurisdictions, which are subject to lower tax rates. Additionally, the Company's effective tax rates for the three and six months ended June 30, 2017 were also impacted by the benefit from restructuring charges and excess tax benefits related to share-based compensation.

As of June 30, 2017, the total amount of gross unrecognized tax benefits was $235.0 million, of which $202.7 million, if recognized, would favorably affect the Company's effective tax rate.