Cover	9 Months Ended
	Sep. 30, 2021 shares
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2021
Document Transition Report	false
Entity File Number	1-16305
Entity Tax Identification Number	91-1969407
Entity Incorporation, State or Country Code	WA
Entity Address, Address Line One	355 110th Ave NE
Entity Address, City or Town	Bellevue
Entity Address, State or Province	WA
Entity Address, Postal Zip Code	98004
City Area Code	(425)
Local Phone Number	454-6363
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Shell Company	false
Document Fiscal Period Focus	Q3
Entity Central Index Key	0001085392
Current Fiscal Year End Date	--12-31
Entity Common Stock, Shares Outstanding	200
Document Fiscal Year Focus	2021
Amendment Flag	false
Entity Emerging Growth Company	false
Entity Registrant Name	PUGET ENERGY INC /WA
Subsidiaries [Member]
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2021
Document Transition Report	false
Entity File Number	1-4393
Entity Tax Identification Number	91-0374630
Entity Incorporation, State or Country Code	WA
Entity Address, Address Line One	355 110th Ave NE
Entity Address, City or Town	Bellevue
Entity Address, State or Province	WA
Entity Address, Postal Zip Code	98004
City Area Code	(425)
Local Phone Number	454-6363
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Shell Company	false
Document Fiscal Period Focus	Q3
Entity Central Index Key	0000081100
Current Fiscal Year End Date	--12-31
Entity Common Stock, Shares Outstanding	85,903,791
Document Fiscal Year Focus	2021
Amendment Flag	false
Entity Emerging Growth Company	false
Entity Registrant Name	PUGET SOUND ENERGY, INC.