Equity Incentive Program (Tables)

3 Months Ended

Mar. 31, 2022

Share-based Payment Arrangement, Noncash Expense [Abstract]

Schedule of Black-Scholes Option-Pricing Assumptions

The expense related to stock options granted in the three months ended March 31, 2022 and 2021 was estimated on the date of grant using a Black-Scholes option-pricing model based on the assumptions shown in the table below:

	Three Months Ended March 31,
	2022	2021
Risk-free interest rate	0.85%	0.06%
Dividend yield	—%	—%
Expected life (years)	4.5	4.5
Volatility	34.3%	36.0%
Fair value at date of grant	$6.29	$6.14

Schedule of SSAR and Stock Options Activity

The following table summarizes the Company's stock-settled stock appreciation right ("SSAR") and stock option activity for the three months ended March 31, 2022:

	SSARs						Stock Options
	Number of Shares	Weighted-Average Exercise Price		Aggregate Intrinsic Value		Weighted-Average Remaining Contractual Term (Years)	Number of Shares	Weighted-Average Exercise Price		Aggregate Intrinsic Value		Weighted-Average Remaining Contractual Term (Years)
(in millions, except share and per share amounts)
Outstanding at December 31, 2021	375,964	$	23.16				3,478,438	$	15.04
Granted	—	—					216,813	21.14
Exercised	(36,759)	21.77					(332,336)	12.62
Forfeited	—	—					(6,244)	20.60
Expired	(95,573)	21.77					—	—
Outstanding at March 31, 2022	243,632	$	23.92	$	—	0.9	3,356,671	$	15.67	$	19.7	3.3
Exercisable at March 31, 2022	243,632	$	23.92	$	—	0.9	2,773,567	$	14.91	$	18.4	2.7

Schedule of Restricted Stock Units Award Activity

The following table summarizes the Company's restricted stock unit ("RSU") activity for the three months ended March 31, 2022:

	Share units	Weighted-average grant date fair value
Unvested at December 31, 2021	1,778,639	$	18.89
Granted	997,294	21.14
Vested (1)	(722,073)	17.98
Forfeited	(65,911)	19.50
Unvested at March 31, 2022	1,987,949	$	20.28

(1) The number of RSUs vested includes shares that the Company withheld on behalf of employees to satisfy statutory tax withholding requirements.

Share-based Payment Arrangement, Performance Shares, Outstanding Activity

The following table summarizes the Company's PSU activity for the three months ended March 31, 2022:

	Share units	Weighted-average grant date fair value
Unvested at December 31, 2021	766,466	$	21.28
Granted	294,935	29.92
Vested (1)	(227,812)	18.44
Forfeited	—	—
Unvested at March 31, 2022	833,589	$	25.12

(1) The number of PSUs vested includes shares that the Company withheld on behalf of employees to satisfy statutory tax withholding requirements.