Stock-Based Compensation Plans (Tables)

3 Months Ended

Mar. 31, 2019

Stock-Based Compensation Plans [Abstract]

Stock-Based Award Plan Activity

A summary of the Company’s stock option (including SARs) activity for the three month period ended March 31, 2019 is presented in the following table (underlying shares in thousands).

	Shares			Weighted-Average Exercise Price (per share)
Outstanding at December 31, 2018		12,352		$	10.93
Granted		1,067		$	27.05
Exercised or settled		(2,271	)	$	8.55
Forfeited		(57	)	$	32.06
Outstanding at March 31, 2019		11,091		$	12.86
Vested at March 31, 2019		8,879		$	9.48

Assumptions Used to Estimate Fair Value of Options Granted

The following assumptions were used to estimate the fair value of options granted (excluding previously disclosed modified awards) during the three month periods ended March 31, 2019 and 2018 using the Black-Scholes option-pricing model.

	Three Month Period Ended March 31, 2019		Three Month Period Ended March 31, 2018
Assumptions
Expected life of options (in years)		6.3		7.0 - 7.5
Risk-free interest rate		2.6%		2.9%
Assumed volatility		31.8%		35.1 - 35.4%
Expected dividend rate		0.0%		0.0%

Restricted Stock Unit Activity

A summary of the Company’s restricted stock unit activity for the three month period ended March 31, 2019 is presented in the following table (underlying shares in thousands).

	Shares			Weighted-Average Grant-Date Fair Value
Non-vested as of December 31, 2018		362		$	31.78
Granted		417		$	27.05
Vested		(28	)	$	32.06
Forfeited		(25	)	$	32.06
Non-vested as of March 31, 2019		726		$	29.01