Retirement Benefits (Tables)

3 Months Ended

Mar. 31, 2021

Retirement Benefits [Abstract]

Schedule of Net Benefit Costs

The following tables summarize the Company’s net periodic benefit cost for the three months ended March 31, 2021 and 2020:

Puget Energy	Qualified Pension Benefits				SERP Pension Benefits				Other Benefits
	Three Months Ended March 31,
(Dollars in Thousands)	2021		2020		2021		2020		2021		2020
Components of net periodic benefit cost:
Service cost	$	6,711	$	5,997	$	115	$	228	$	41	$	49
Interest cost	5,578		6,298		293		378		77		91
Expected return on plan assets	(12,081)		(12,502)		—		—		(91)		(97)
Amortization of prior service cost	(476)		(495)		87		87		2		—
Amortization of net loss (gain)	2,830		1,981		587		586		(10)		(22)
Net periodic benefit cost	$	2,562	$	1,279	$	1,082	$	1,279	$	19	$	21

Puget Sound Energy	Qualified Pension Benefits				SERP Pension Benefits				Other Benefits
	Three Months Ended March 31,
(Dollars in Thousands)	2021		2020		2021		2020		2021		2020
Components of net periodic benefit cost:
Service cost	$	6,711	$	5,997	$	115	$	228	$	41	$	49
Interest cost	5,578		6,298		293		378		77		91
Expected return on plan assets	(12,081)		(12,504)		—		—		(91)		(97)
Amortization of prior service cost	(378)		(393)		87		87		2		—
Amortization of net loss (gain)	5,311		4,656		635		659		(15)		(36)
Net periodic benefit cost	$	5,141	$	4,054	$	1,130	$	1,352	$	14	$	7

Schedule of Changes in Projected Benefit Obligations

The following table summarizes the Company’s change in benefit obligation for the periods ended March 31, 2021 and December 31, 2020:

Puget Energy and Puget Sound Energy	Qualified Pension Benefits				SERP Pension Benefits				Other Benefits
	Three Months Ended		Year Ended		Three Months Ended		Year Ended		Three Months Ended		Year Ended
(Dollars in Thousands)	March 31, 2021		December 31, 2020		March 31, 2021		December 31, 2020		March 31, 2021		December 31, 2020
Change in benefit obligation:
Benefit obligation at beginning of period	$	849,383	$	774,305	$	46,742	$	63,000	$	12,114	$	11,627
Amendments	—		—		—		—		—		44
Service cost	6,711		24,337		115		756		41		190
Interest cost	5,578		25,180		293		1,464		77		368
Curtailment Loss / (Gain)	—		—		—		—		—		—
Actuarial loss (gain)	—		69,413		—		3,663		—		604
Benefits paid	(11,625)		(42,775)		(496)		(22,141)		(237)		(906)
Medicare part D subsidy received	—		—		—		—		196		187
Administrative Expense	—		(1,077)		—		—		—		—
Benefit obligation at end of period	$	850,047	$	849,383	$	46,654	$	46,742	$	12,191	$	12,114