Commitments and contingencies - Estimates of Future Commitments (Detail) $ in Thousands	Jun. 30, 2022 USD ($)	Nov. 17, 2020 lawsuit
Commitments Disclosure [Line Items]
Year 1	$ 357,346
Year 2	205,699
Year 3	177,456
Year 4	139,426
Year 5	98,402
Thereafter	1,106,666
Total	2,084,995
Power purchase
Commitments Disclosure [Line Items]
Year 1	110,990
Year 2	53,417
Year 3	53,594
Year 4	32,367
Year 5	12,397
Thereafter	148,887
Total	411,652
Gas supply and service agreements
Commitments Disclosure [Line Items]
Year 1	108,351
Year 2	80,109
Year 3	52,985
Year 4	38,258
Year 5	25,596
Thereafter	166,289
Total	471,588
Service agreements
Commitments Disclosure [Line Items]
Year 1	66,323
Year 2	58,865
Year 3	57,395
Year 4	55,144
Year 5	46,585
Thereafter	323,799
Total	608,111
Capital projects
Commitments Disclosure [Line Items]
Year 1	58,522
Year 2	0
Year 3	0
Year 4	0
Year 5	0
Thereafter	0
Total	58,522
Land easements and others
Commitments Disclosure [Line Items]
Year 1	13,160
Year 2	13,308
Year 3	13,482
Year 4	13,657
Year 5	13,824
Thereafter	467,691
Total	$ 535,122
Mountain View Fire
Commitments Disclosure [Line Items]
Number of active lawsuits \| lawsuit		10
Number of lawsuits filed by groups of individual plaintiffs \| lawsuit		5
Number of lawsuits filed by insurance companies \| lawsuit		3

Commitments Disclosure [Line Items]

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Number of Lawsuits

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Number of Lawsuits Filed by Groups of Individual Plaintiffs

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Number of Lawsuits Filed by Insurance Companies

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

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Amount of contractual 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).

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Amount of contractual 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).

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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).

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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).

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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).

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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).

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