Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2018

Stock-Based Compensation [Abstract]

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 six month periods ended June 30, 2018 and 2017 using the Black-Scholes option-pricing model.

	Six Month Period Ended June 30, 2018			Six Month Period Ended June 30, 2017
Assumptions:
Expected life of options (in years)		7.0 - 7.5			5.0 - 6.3
Risk-free interest rate		2.9 - 3.0	%		1.9 - 2.1	%
Assumed volatility		34.4 - 35.4	%		41.2 - 45.8	%
Expected dividend rate		0.0	%		0.0	%

Stock-Based Award Plan Activity

A summary of the Company’s stock option (including SARs) activity for the six month period ended June 30, 2018 is presented in the following table (underlying shares in thousands).

	Shares			Weighted-Average Exercise Price (per share)
Outstanding at December 31, 2017		12,834		$	9.54
Granted		800		$	32.04
Exercised or settled		(619	)	$	8.35
Forfeited		(316	)	$	15.40
Outstanding at June 30, 2018		12,699		$	10.87
Vested at June 30, 2018		8,806		$	9.10

Restricted Stock Unit Activity

A summary of the Company’s restricted stock unit activity for the six month period ended June 30, 2018 is presented in the following table (underlying shares in thousands).

	Shares			Weighted-Average Grant-Date Fair Value
Non-vested as of December 31, 2017		-		$	-
Granted		352		$	32.04
Vested		-		$	-
Forfeited		(6	)	$	32.06
Non-vested as of June 30, 2018		346		$	32.04