Commitments and Contingencies - Certain Fuel, Transportation and Purchased Energy Commitments (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Coal, Gas and Transportation Commitments
Commitments and Contingencies
Purchases under coal, gas and transportation arrangement	$ 600	$ 500	$ 600
Minimum purchase commitment
2022	122
2023	54
2024	63
2025	62
2026	51
Thereafter	26
Total	378
Purchases under power contracts	600	500	600
Renewable Purchased Power Agreements
Commitments and Contingencies
Purchases under coal, gas and transportation arrangement	12,800	1,800	2,600
Minimum purchase commitment
2022	1,566
2023	1,036
2024	617
2025	382
2026	289
Thereafter	1,071
Total	4,961
Purchases under power contracts	$ 12,800	$ 1,800	$ 2,600

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- Definition

The amount the entity spent under long-term purchase commitments during the reporting period.

+ References

No definition available.

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Amount of fixed and determinable portion of unrecorded unconditional purchase obligation to be paid in fifth 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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 440
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123406679&loc=d3e25336-109308

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Amount of fixed and determinable portion of unrecorded unconditional purchase 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

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Amount of fixed and determinable portion of unrecorded unconditional purchase 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

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- Definition

Amount of fixed and determinable portion of unrecorded unconditional purchase 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

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- Definition

Amount of fixed and determinable portion of unrecorded unconditional purchase 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 the unrecorded obligation to transfer funds in the future for fixed or minimum amounts or quantities of goods or services at fixed or minimum prices (for example, as in take-or-pay contracts or throughput contracts).

+ References

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- Definition

Amount of fixed and determinable portion of unrecorded unconditional purchase obligation to be paid after fifth 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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 440
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123406679&loc=d3e25336-109308

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