Stock-Based Incentive Compensation Plans and Employee Benefit Plans - Stock Based Incentive Compensation (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
Income tax benefit recognized related to LTIPs	$ 11	$ 9	$ 7
Actual tax benefit realized for tax deductions	$ 4	$ 5	$ 12
Performance Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period	3 years
Shares
Nonvested, beginning of period (in shares)	3,900,000,000
Granted (in shares)	2,095,000,000
Forfeited or cancelled (in shares)	(1,017,000,000)
Vested and released to participants (in shares)	(315,000,000)
Nonvested, end of period (in shares)	4,663,000,000	3,900,000,000
Weighted-Average Grant Date Fair Value
Nonvested, beginning of period (in dollars per share)	$ 26.58
Granted (in dollars per share)	21.89	$ 23.82	$ 31.16
Forfeited or cancelled (in dollars per share)	26.44
Vested and released to participants (in dollars per share)	26.79
Nonvested, end of period (in dollars per share)	$ 24.48	$ 26.58
Remaining average contractual life of nonvested shares outstanding (in years)	1 year 2 months 12 days
Aggregate Intrinsic Value	$ 90
Total intrinsic value of awards received by participants	7	$ 9	$ 36
Total grant date fair values of performance and stock awards which vested during the period	$ 8	$ 9	$ 20
Stock Awards
Shares
Nonvested, beginning of period (in shares)	1,289,000,000
Granted (in shares)	1,609,000,000
Forfeited or cancelled (in shares)	(91,000,000)
Vested and released to participants (in shares)	(440,000,000)
Nonvested, end of period (in shares)	2,367,000,000	1,289,000,000
Weighted-Average Grant Date Fair Value
Nonvested, beginning of period (in dollars per share)	$ 25.71
Granted (in dollars per share)	24.20	$ 21.53	$ 31.07
Forfeited or cancelled (in dollars per share)	26.23
Vested and released to participants (in dollars per share)	25.26
Nonvested, end of period (in dollars per share)	$ 24.75	$ 25.71
Remaining average contractual life of nonvested shares outstanding (in years)	1 year 4 months 24 days
Aggregate Intrinsic Value	$ 66
Total intrinsic value of awards received by participants	11	$ 12	$ 15
Total grant date fair values of performance and stock awards which vested during the period	11	12	9
Performance and Stock Awards
Weighted-Average Grant Date Fair Value
Unrecognized compensation cost related to non-vested performance and stock awards	$ 58
Weighted average period of recognition (in years)	1 year 8 months 12 days
Operation And Maintenance Expense
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
LTIP compensation expense	$ 48	$ 38	$ 28
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance under long-term incentive plans (in shares)	14,000,000