Stock-Based Compensation Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2015

Stock-Based Compensation Expense and Related Tax Benefit [Table Text Block]

For the three and six months ended June 30, stock-based compensation expense and the related tax benefit were as follows:



	Three Months Ended June 30,				Six Months Ended June 30,
	2015		2014		2015		2014
	(in thousands)
Stock options	$	643	$	546	$	1,292	$	1,100
Restricted stock units	3,079		4,094		6,405		7,894
Unrestricted stock awards	167		230		300		460
Total stock-based compensation	$	3,889	$	4,870	$	7,997	$	9,454

Related tax benefit	$	1,225	$	1,388	$	2,374	$	2,676

Stock Options, Valuation Assumptions [Table Text Block]

The fair values of stock options granted were estimated at the date of grant using the Black-Scholes option-pricing model with the following weighted average assumptions:



	Three Months Ended June 30,				Six Months Ended June 30,
	2015		2014		2015		2014
Dividend yield	—	%	—	%	—	%	—	%
Expected volatility	33.9	%	—	%	34.5	%	39.8	%
Risk-free interest rate	1.6	%	—	%	1.7	%	1.7	%
Expected term (years)	5.5		—		5.5		5.5

Employee Stock Options Activity [Table Text Block]

A summary of our stock option activity for the six months ended June 30 is as follows:



	Shares		Weighted Average Exercise Price per Share		Weighted Average Remaining Contractual Life	Aggregate Intrinsic Value⁽¹⁾		Weighted Average Grant Date Fair Value
	(in thousands)				(years)	(in thousands)
Outstanding, January 1, 2014	1,180		$	54.79	4.6	$	1,300
Granted	147		35.19					$	13.64
Exercised	(33	)	23.70			510
Expired	(10	)	43.82
Outstanding, June 30, 2014	1,284		$	53.43	4.7	$	1,364

Outstanding, January 1, 2015	1,123		$	51.90	4.4	$	1,676
Granted	207		35.30					$	12.15
Exercised	(23	)	36.05			26
Forfeited	(17	)	37.47
Expired	(158	)	54.25
Outstanding, June 30, 2015	1,132		$	49.12	5.7	$	—

Exercisable June 30, 2015	743		$	55.53	3.9	$	—

Expected to vest, June 30, 2015	376		$	36.90	9.0	$	—

⁽¹⁾

The aggregate intrinsic value of outstanding stock options represents amounts that would have been received by the optionees had all in- the-money options been exercised on that date. Specifically, it is the amount by which the market value of our stock exceeded the exercise price of the outstanding in-the-money options before applicable income taxes, based on our closing stock price on the last business day of the period. The aggregate intrinsic value of stock options exercised during the period is calculated based on our stock price at the date of exercise.

Restricted Stock Units, Valuation Assumptions

The weighted-average assumptions used to estimate the fair value of performance-based restricted stock units granted and the resulting weighted average fair-value are as follows:



	Three Months Ended June 30,						Six Months Ended June 30,
	2015			2014			2015			2014
Dividend yield	—		%	—		%	—		%	—		%
Expected volatility	28.4		%	34.0		%	30.1		%	32.4		%
Risk-free interest rate	0.9		%	0.6		%	0.7		%	0.4		%
Expected term (years)	2.7			2.6			2.1			2.0

Weighted-average fair value	$	36.65		$	41.47		$	33.48		$	34.87

Restricted Stock Units Award Activity [Table Text Block]

The following table summarizes restricted stock unit activity for the six months ended June 30:



	Number of Restricted Stock Units		Weighted Average Grant Date Fair Value		Aggregate Intrinsic Value⁽¹⁾
	(in thousands)				(in thousands)
Outstanding, January 1, 2014	658
Granted ⁽²⁾	320		$	35.49
Released	(261	)			$	12,818
Forfeited	(21	)
Outstanding, June 30, 2014	696

Outstanding, January 1, 2015	682
Granted ⁽²⁾	319		$	35.30
Released	(282	)			$	11,593
Forfeited	(36	)
Outstanding, June 30, 2015	683

Vested but not released, June 30, 2015	5				$	171

Expected to vest, June 30, 2015	551				$	18,965


⁽¹⁾	The aggregate intrinsic value is the market value of the stock, before applicable income taxes, based on the closing price on the stock release dates or at the end of the period for restricted stock units expected to vest.


⁽²⁾	Restricted stock units granted in 2014 and 2015 do not include awards under the Performance Award Agreement for the respective years, as these awards are not granted until attainment of annual performance goals has been determined at the conclusion of the performance period, which had not occurred as of June 30, 2014 and 2015, respectively.

Nonrestricted Stock Awards Activity [Table Text Block]

The following table summarizes unrestricted stock award activity for the three and six months ended June 30:



	Three Months Ended June 30,				Six Months Ended June 30,
	2015		2014		2015		2014
	(in thousands, except per share data)
Shares of unrestricted stock granted	5		6		8		13

Weighted average grant date fair value per share	$	36.31	$	35.82	$	38.47	$	38.23

Employee Stock Purchase Plan (ESPP) Activity [Table Text Block]

The following table summarizes ESPP activity for the three and six months ended June 30:



	Three Months Ended June 30,		Six Months Ended June 30,
	2015	2014	2015	2014
	(in thousands)
Shares of stock sold to employees⁽¹⁾	18	20	28	34


⁽¹⁾	Stock sold to employees during each fiscal quarter under the ESPP is associated with the offering period ending on the last day of the previous fiscal quarter.