Stock Compensation Plans and Other Compensation Arrangements (Tables)

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

Stock Award Rollforward Activity

Stock award activity for the years ended December 31, 2018, 2019 and 2020, is presented in the table below. Vested awards do not include any adjustments to reflect the final performance measure for issued shares.

	Stock Awards (in thousands)	Weighted- Average Grant Date Fair Value Per Share		Weighted- Average Remaining Contractual Term (in years)
Outstanding at January 1, 2018	938	$	192	1.0
Granted	376	321
Vested	(455)	181
Forfeited	(63)	250
Outstanding at December 31, 2018	796	$	244	0.8
Granted	339	274
Vested	(383)	222
Forfeited	(51)	280
Outstanding at December 31, 2019	701	$	278	0.9
Granted	262	350
Vested	(296)	305
Forfeited	(64)	303
Outstanding at December 31, 2020	603	$	311	1.4

Cash Units and Cash Performance Units Aggregate Payout Amount [Table Text Block]

The following table presents the minimum and maximum aggregate payout amounts related to those cash awards granted for the periods presented:

	Year Ended December 31
$ in millions	2020		2019		2018
Minimum aggregate payout amount	$	31	$	36	$	36
Maximum aggregate payout amount	175		203		205