Equity Incentive Program (Tables)

6 Months Ended

Jun. 30, 2020

Share-based Payment Arrangement, Noncash Expense [Abstract]

Schedule of Black-Scholes Option-Pricing Assumptions

The expense related to stock options granted in the six months ended June 30, 2020 and 2019 was estimated on the date of grant using a Black-Scholes option-pricing model based on the assumptions shown in the table below:


	Six Months Ended June 30,
	2020					2019
Risk-free interest rate	0.16%	to	1.42%	2.29%	to	2.44%
Dividend yield	—%					—%
Expected life (years)	4.3	to	4.5	4.5
Volatility	38.8%	to	40.6%	41.8%	to	42.9%

Fair value at date of grant	$4.78	to	$5.95	$6.22	to	$6.55

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 six months ended June 30, 2020 (in millions, except share and per share amounts):


	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)
Outstanding at December 31, 2019	596,537	$	22.72				5,377,148	$	17.51
Granted	—	—					888,891	16.76

Exercised	—	—					(123,574)	12.43
Forfeited	—	—					(139,969)	16.59
Expired	—	—					(100,791)	19.73
Outstanding at June 30, 2020	596,537	$	22.72	$	—	1.9	5,901,705	$	17.48	$	6.0	3.4

Exercisable at June 30, 2020	596,537	$	22.72	$	—	1.9	4,335,643	$	17.92	$	5.8	2.5

Schedule of Restricted Stock Units Award Activity

The following table summarizes the Company's restricted stock unit ("RSU") activity for the six months ended June 30, 2020:


	Share units	Weighted-average grant date fair value
Unvested at December 31, 2019	2,261,114	$	15.99
Granted	1,406,939	16.52

Vested ⁽¹⁾	(1,016,274)	16.26
Forfeited	(635,437)	16.24
Unvested at June 30, 2020	2,016,342	$	16.19

⁽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 six months ended June 30, 2020:


	Share units	Weighted-average grant date fair value
Unvested at December 31, 2019	844,789	$	15.90
Granted	322,178	16.14

Vested ⁽¹⁾	(176,154)	15.38
Forfeited	(61,589)	17.05
Unvested at June 30, 2020	929,224	$	16.01

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