Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement, Noncash Expense [Abstract]

Stock-Based Compensation Expense and Related Tax Benefit

Total stock-based compensation expense and the related tax benefit were as follows:

	Year Ended December 31,
In thousands	2020		2019		2018
Stock options	$	1,944	$	1,770	$	3,675
Restricted stock units	22,285		24,560		26,859
Unrestricted stock awards	824		630		729
Phantom stock units	3,720		3,301		2,165
Total stock-based compensation	$	28,773	$	30,261	$	33,428
Related tax benefit	$	5,086	$	5,390	$	6,019

Employee Stock Options Activity

A summary of our stock option activity is as follows:

	Shares	Weighted Average Exercise Price per Share		Weighted Average Remaining Contractual Life	Aggregate Intrinsic Value		Weighted Average Grant Date Fair Value
	In thousands			Years	In thousands
Outstanding, January 1, 2018	956	$	47.10	6.3	$	21,965
Converted upon acquisition	42	51.86					$	14.86
Granted	122	68.21					24.29
Exercised	(152)	38.99			4,520
Forfeited	(7)	60.03
Expired	(66)	95.31
Outstanding, December 31, 2018	895	$	47.93	6.2	$	4,806
Granted	76	76.55					$	26.20
Exercised	(489)	43.55			15,759
Forfeited	(13)	67.34
Expired	(11)	66.24
Outstanding, December 31, 2019	458	$	56.38	7.0	$	12,641
Granted	83	84.39					$	26.37
Exercised	(103)	53.99			2,061
Forfeited	(5)	83.94
Outstanding, December 31, 2020	433	$	61.95	6.9	$	14,697
Exercisable, December 31, 2020	268	$	51.85	5.8	$	11,810

Stock Options, Valuation Assumptions

The weighted average assumptions used to estimate the fair value of stock options granted and the resulting weighted average fair value are as follows:

	Year Ended December 31,
	2020		2019		2018
Expected volatility	32.3	%	31.7	%	30.5	%
Risk-free interest rate	1.3	%	1.7	%	2.8	%
Expected term (years)	5.3		6.1		6.1

Restricted Stock Units Award Activity

The following table summarizes restricted stock unit activity:

	Number of Restricted Stock Units	Weighted Average Grant Date Fair Value		Aggregate Intrinsic Value
	In thousands			In thousands
Outstanding, January 1, 2018	556	$	47.68
Converted upon acquisition	579	69.40
Granted	387	57.48
Released (1)	(593)			$	32,567
Forfeited	(112)
Outstanding, December 31, 2018	817	$	59.70
Granted	404	62.97
Released (1)	(471)			$	29,304
Forfeited	(66)
Outstanding, December 31, 2019	684	$	64.38
Granted	262	83.42
Released (1)	(363)	65.25		$	23,702
Forfeited	(39)	71.96
Outstanding, December 31, 2020	544	$	71.79
Vested but not released, December 31, 2020	50			$	4,836

Restricted Stock Units, Valuation Assumptions

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

	Year Ended December 31,
	2020			2019			2018
Expected volatility	44.9		%	31.4		%	28.0		%
Risk-free interest rate	1.0		%	2.5		%	2.2		%
Expected term (years)	1.8			1.6			2.1
Weighted average fair value	$	93.97		$	61.25		$	78.56

Schedule of Other Share-based Compensation, Activity

The following table summarizes phantom stock unit activity:

	Number of Phantom Stock Units	Weighted Average Grant Date Fair Value		Aggregate Intrinsic Value
	In thousands			In thousands
Outstanding, January 1, 2018	63	$	62.53
Converted upon acquisition	21
Granted	41	66.67
Released	(35)			$	2,409
Forfeited	(7)
Outstanding, December 31, 2018	83	$	61.80
Converted upon acquisition	—
Granted	55	60.49
Released	(42)			$	2,625
Forfeited	(7)
Outstanding, December 31, 2019	89	$	62.85
Granted	38	87.27
Released	(40)	63.87		$	2,971
Forfeited	(5)	70.99
Outstanding, December 31, 2020	82	$	73.13