Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2019

Share-based Payment Arrangement [Abstract]

Schedule of Valuation Assumptions

For stock options granted during the six months ended June 30, 2018 valued using the Black-Scholes option valuation model, we used the following assumptions:

	Six Months Ended
	June 30, 2018
Risk-free interest rate	2.65	%
Expected dividend yield	—	%
Expected term of option	4 years
Expected volatility	45.0	%
Weighted-average expected volatility	45.0	%

For performance-based restricted stock units granted during the six months ended June 30, 2019 valued using the Monte Carlo Simulation valuation model, we used the following assumptions:

	Six Months Ended
	June 30, 2019
Risk-free interest rate	1.8% - 2.48%
Expected dividend yield	—	%
Expected volatility	45.0	%
Weighted-average expected volatility	45.0	%

Schedule of Stock Option Activity and Weighted Average Exercise Prices

A summary of stock option activity and weighted-average exercise prices during the six months ended June 30, 2019 follows:

	Options		Weighted- Average Exercise Price		Weighted-Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value as of June 30, 2019
Outstanding at January 1, 2019	792,943		$	47.59
Granted	—		—
Forfeited or expired	(69,670	)	54.47
Exercised	(21,118	)	34.76
Outstanding at June 30, 2019	702,155		$	47.54	4.0	$	6,116
Options exercisable at June 30, 2019	612,544		$	47.28	2.7	$	5,396

Schedule of Restricted Stock and Restricted Stock Units Activity and Weighted-Average Grant Date Fair Value

The following table summarizes the restricted stock and restricted stock unit activity and weighted average grant-date fair values for the six months ended June 30, 2019:

	Shares		Weighted-Average Grant Date Fair Value
Non-vested at January 1, 2019	311,000		$	42.66
Granted	240,539		48.97
Forfeited	(21,574	)	47.55
Vested	(108,413	)	36.47
Non-vested at June 30, 2019	421,552		$	47.60