SCHEDULE I CONDENSED FINANCIAL INFORMATION OF PUGET ENERGY - Condensed Statements of Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Condensed Financial Statements, Captions [Line Items]
Nonutility Expense And Other	$ (58,281)	$ (43,425)	$ (47,907)
Interest expense	(352,092)	(373,822)	(356,638)
Income Tax Expense (Benefit)	(24,515)	(1,664)	(17,073)
Net income (loss)	260,849	182,717	210,708
Comprehensive income (loss)	319,854	180,429	203,761
Condensed Cash Flow Statements, Captions [Line Items]
Net Cash Provided by (Used in) Operating Activities	826,598	727,568	527,336
Payments for (Proceeds from) Other Investing Activities	(1,367)	(5,340)	(6,908)
Net Cash Provided by (Used in) Investing Activities	(920,777)	(902,796)	(952,479)
Payments of Dividends	106,420	45,421	64,220
Proceeds from Contributions from Parent	210,000	4,575	0
Proceeds from Issuance of Long-term Debt	961,538	644,690	689,351
Repayments of Long-term Debt	502,410	450,000	0
Net Cash Provided by (Used in) Financing Activities	115,478	190,933	435,727
Net increase (decrease) in cash, cash equivalents, and restricted cash	21,299	15,705	10,584
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	103,150	81,851	66,146	$ 55,562
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Nonutility Expense And Other	(913)	(1,579)	(1,495)
Equity In Net Income (Loss) Of Subsidiaries	337,405	277,654	294,724
Investment Income, Interest	4,261	4,760	6,643
Interest expense	(100,002)	(123,592)	(111,716)
Income Tax Expense (Benefit)	20,098	25,474	22,552
Net income (loss)	260,849	182,717	210,708
Comprehensive income (loss)	319,854	180,429	203,761
Condensed Cash Flow Statements, Captions [Line Items]
Net Cash Provided by (Used in) Operating Activities	143,691	38,280	68,724
Adjustments to Additional Paid in Capital, Other	21,783	0	210,000
Payments for (Proceeds from) Loans Receivable from Subsidiary	0	31,043	41,708
Net Cash Provided by (Used in) Investing Activities	(21,783)	(31,043)	(251,708)
Payments of Dividends	106,420	45,421	64,220
Proceeds from Contributions from Parent	(210,000)	(4,575)	0
Proceeds from Issuance of Long-term Debt	515,475	644,690	246,200
Repayments of Long-term Debt	734,000	609,400	0
Issue costs and others	1,367	1,838	116
Net Cash Provided by (Used in) Financing Activities	(116,312)	(7,394)	181,864
Net increase (decrease) in cash, cash equivalents, and restricted cash	5,596	(157)	(1,120)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 6,386	$ 790	$ 947	$ 2,067