Stock-Based Compensation Plans (Tables)

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

Schedule of Share-based Compensation Activity

A summary of the 2020 RSUs, and PSUs granted to certain NEOs, employees, and the Board of Directors is presented below (shares/units in thousands):

Grant Year	Award Type	Number of Units Awarded(1)	Vesting Terms
2020	RSU	82	Vest equally over three service periods ending in 2021, 2022, and 2023
2020	PSU	37	Three-year performance and service period ending in 2022
2020	RSU	12	One year service period ending in 2021

(1) PSUs presented are based on the target number of units for the original PSU grant.

Activity for Awards Made Outside of Share-Based Compensation Plans

Activity for our RSAs, RSUs, and PSUs is presented below (shares/units in thousands):

	PSUs			RSAs and RSUs			Total
(in thousands, except grant date values)	Number of Shares/Units	Weighted Average Grant Date Fair Value		Number of Shares/Units	Weighted Average Grant Date Fair Value		Number of Shares/Units	Weighted Average Grant Date Fair Value
Balance as of December 31, 2017	124	$	51.59	316	$	45.51	440	$	47.23
Granted	256	$	68.32	193	$	84.78	449	$	75.39
Performance adjustment(1)	70	$	47.01	—	$	—	70	$	47.01
Vested	(129)	$	47.01	(217)	$	46.35	(346)	$	46.60
Canceled/forfeited	—	$	—	(17)	$	54.49	(17)	$	54.49
Balance as of December 31, 2018	321	$	65.77	275	$	72.03	596	$	68.66
Granted	58	$	92.90	130	$	94.42	188	$	93.96
Performance adjustment(1)	87	$	55.75	—	$	—	87	$	55.75
Vested	(152)	$	55.75	(135)	$	68.15	(287)	$	61.57
Canceled/forfeited	—	$	—	(5)	$	77.59	(5)	$	77.59
Balance as of December 31, 2019	314	$	72.84	265	$	85.07	579	$	78.45
Granted	37	$	182.45	94	$	150.12	131	$	159.3
Performance adjustment(1)	41	$	90.73	—	$	—	41	$	90.73
Vested	(90)	$	90.73	(121)	$	90.01	(211)	$	90.32
Canceled/forfeited	—	$	—	(3)	$	121.39	(3)	$	121.39
Balance as of December 31, 2020	302	$	83.40	235	$	107.90	537	$	94.14

(1)Adjustment to number of target units awarded for PSUs based on achievement of performance and TSR goals.

Summary of Unrecognized Stock-based Compensation Expense

A summary of total unrecognized stock-based compensation expense related to RSAs, RSUs, and PSUs (based on current performance estimates), at December 31, 2020 is presented below:

(in millions, except years)	December 31, 2020		Weighted Average Remaining Vesting Period (Years)
Unrecognized expense:
RSA	$	0.8	1.02
RSU	9.9		2.29
PSU	14.2		2.72
Total	$	24.9	2.49