Common Stock (Tables)

6 Months Ended

Jun. 30, 2017

Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan

The following table provides a summary of the impact of our outstanding stock-based compensation plans on the results of operations for the periods presented:



	Three Months Ended June 30,						Six Months Ended June 30,
	2017			2016			2017			2016
	(in thousands)

Stock-based compensation expense	$	5,372		$	6,444		$	9,826		$	11,126
Income tax benefit	(2,010		)	(2,452		)	(3,676		)	(4,233		)
Net stock-based compensation expense	$	3,362		$	3,992		$	6,150		$	6,893

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions

he Compensation Committee of our Board of Directors awarded SARs to our executive officers during the six months ended June 30, 2017 and 2016. The fair value of each SAR award was estimated on the date of grant using a Black-Scholes pricing model using the following assumptions:



	Six Months Ended June 30,
	2017			2016

Expected term of award (in years)	6			6
Risk-free interest rate	2.0		%	1.8		%
Expected volatility	53.3		%	54.5		%
Weighted-average grant date fair value per share	$	38.58		$	26.96

Schedule of Share-based Compensation, Stock Appreciation Rights Award Activity

The following table presents the changes in our SARs for the six months ended June 30, 2017:



	Number of SARs	Weighted-Average Exercise Price		Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2016	244,078	$	41.36	6.9	$	7,620
Awarded	54,142	74.57		—	—
Outstanding at June 30, 2017	298,220	47.39		7.0	1,158
Exercisable at June 30, 2017	186,248	39.38		5.8	1,093

Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity

The following table presents the changes in non-vested time-based awards to all employees, including executive officers, for the six months ended June 30, 2017:



	Shares		Weighted-Average Grant Date Fair Value

Non-vested at December 31, 2016	479,642		$	56.09
Granted	248,946		67.02
Vested	(202,427	)	56.43
Forfeited	(5,311	)	67.20
Non-vested at June 30, 2017	520,850		61.06

The following table presents the weighted-average grant date fair value per share and related information as of/for the periods presented:



	As of/Six Months Ended June 30,
	2017		2016
	(in thousands, except per share data)

Total intrinsic value of time-based awards vested	$	13,103	$	13,314
Total intrinsic value of time-based awards non-vested	22,454		31,506
Market price per common share as of June 30,	43.11		57.61
Weighted-average grant date fair value per share	67.02		57.11

Restricted Stock Awards, Market-Based, Valuation assumptions

he Compensation Committee of our Board of Directors awarded a total of 28,069 market-based restricted shares to our executive officers during the six months ended June 30, 2017. In addition to continuous employment, the vesting of these shares is contingent on our total stockholder return ("TSR"), which is essentially our stock price change including any dividends as compared to the TSR of a group of peer companies. The shares are measured over a three-year period ending on December 31, 2019, and can result in a payout between 0 percent and 200 percent of the total shares awarded. The weighted-average grant date fair value per market-based share for these awards was computed using the Monte Carlo pricing model using the following assumptions:



	Six Months Ended June 30,
	2017			2016

Expected term of award (in years)	3			3
Risk-free interest rate	1.4		%	1.2		%
Expected volatility	51.4		%	52.3		%
Weighted-average grant date fair value per share	$	94.02		$	72.54

Schedule of Nonvested Performance-based Units Activity

The following table presents the change in non-vested market-based awards during the six months ended June 30, 2017:



	Shares	Weighted-Average Grant Date Fair Value per Share

Non-vested at December 31, 2016	48,420	$	64.97
Granted	28,069	94.02
Non-vested at June 30, 2017	76,489	75.63

The following table presents the weighted-average grant date fair value per share and related information as of/for the periods presented:



	As of /Six Months Ended June 30,
	2017		2016
	(in thousands, except per share data)

Total intrinsic value of market-based awards vested	$	—	$	1,174
Total intrinsic value of market-based awards non-vested	3,297		4,871
Market price per common share as of June 30,	43.11		57.61
Weighted-average grant date fair value per share	94.02		72.54