Stock Based Compensation (Tables)

3 Months Ended

Mar. 31, 2017

Stock Based Compensation [Abstract]

Stock Based Compensation Expense

The following table provides information regarding the Company's stock-based compensation expense (in thousands):

	Three months ended March 31,
	2017			2016
Stock based compensation		$	21,049		$	18,979
Tax effect recognized in net income			7,367			6,643

Weighted Average Assumptions Used to Value Option Grants

	Three months ended March 31,
	2017		2016
Risk-free interest rate (%)		2.09		1.41
Expected option life (years)		5.27		5.20
Expected volatility (%)		18.87		21.63
Expected dividend yield (%)		0.69		0.70

Cash received from option exercises for the three months ended March 31, 2017, and 2016 was $12.9 million and $1.9 million, respectively.