Commitments and Contingencies - Schedule of Long-term Commitments (Detail) $ in Millions	Mar. 31, 2021 USD ($)
Other Commitments [Line Items]
2021	$ 722
2022	368
2023	288
2024	225
2025	206
Thereafter	2,100
Total future minimum payments	3,909
Purchased Power [Member]
Other Commitments [Line Items]
2021	35
2022	0
2023	0
2024	0
2025	0
Thereafter	0
Total future minimum payments	35
Transportation [Member]
Other Commitments [Line Items]
2021	175
2022	233
2023	212
2024	207
2025	188
Thereafter	1,998
Total future minimum payments	3,013
Capital Projects [Member]
Other Commitments [Line Items]
2021	300
2022	75
2023	57
2024	0
2025	0
Thereafter	0
Total future minimum payments	432
Fuel and Gas Supply [Member]
Other Commitments [Line Items]
2021	197
2022	42
2023	1
2024	0
2025	0
Thereafter	0
Total future minimum payments	240
Long-term Service Agreements [Member]
Other Commitments [Line Items]
2021	10
2022	12
2023	15
2024	15
2025	16
Thereafter	54
Total future minimum payments	122
Operating Leases [Member]
Other Commitments [Line Items]
2021	2
2022	3
2023	3
2024	3
2025	2
Thereafter	48
Total future minimum payments	61
Demand Side Management [Member]
Other Commitments [Line Items]
2021	3
2022	3
2023	0
2024	0
2025	0
Thereafter	0
Total future minimum payments	$ 6

Contractual obligation due after fourth year.

No definition available.

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- Definition

Amount of contractual obligation, including but not limited to, long-term debt, capital lease obligations, operating lease obligations, purchase obligations, and other commitments.

+ References

No definition available.

+ Details

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- Definition

Amount of contractual obligation to be paid in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

No definition available.

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- Definition

Amount of contractual obligation to be paid in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

No definition available.

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Amount of contractual obligation to be paid in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

No definition available.

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Amount of contractual obligation to be paid in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

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- Definition

Amount of contractual obligation to be paid in remainder of current fiscal year.

+ References

No definition available.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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