Stockholders' Equity Accumulated Other Comprehensive Income (loss) - Reclassifications of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020		Dec. 31, 2019
Amortization of defined benefit pension and postretirement plan items:
Income tax benefit		$ (29,231)	$ (23,538)		$ (21,114)
Accumulated other comprehensive income (loss)		1,303	(2,865)		(6,267)
Other Comprehensive Income (Loss), before Reclassifications, before Tax		7,337	4,838
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		(3,169)	(1,436)
Other Comprehensive Income (Loss), Net of Tax		4,168	3,402
Accumulated (Gain) Loss from Commodity Contracts Cash Flows Hedges [Member]
Amortization of defined benefit pension and postretirement plan items:
Accumulated other comprehensive income (loss)		4,571	2,309		(1,334)
Other Comprehensive Income (Loss), before Reclassifications, before Tax		7,075	5,400
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		(4,813)	(1,757)
Other Comprehensive Income (Loss), Net of Tax		2,262	3,643
Accumulated (Gain) Loss from Interest Rate Swap Cash Flows Hedges
Amortization of defined benefit pension and postretirement plan items:
Accumulated other comprehensive income (loss)		0	(28)		0
Other Comprehensive Income (Loss), before Reclassifications, before Tax		0	16
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		28	(44)
Other Comprehensive Income (Loss), Net of Tax		28	(28)
AOCI Changes For Defined Benefit Pension And Postretirement Plans [Member]
Amortization of defined benefit pension and postretirement plan items:
Accumulated other comprehensive income (loss)		(3,268)	(5,146)		(4,933)
Other Comprehensive Income (Loss), before Reclassifications, before Tax		262	(578)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		1,616	365
Other Comprehensive Income (Loss), Net of Tax		1,878	(213)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Amortization of defined benefit pension and postretirement plan items:
Net of tax		3,169	1,436		728
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment [Member]
Amortization of defined benefit pension and postretirement plan items:
Prior service cost	[1]	77	77		77
Net gain		(2,243)	(592)	[1]	(2,600)	[1]
Total before income taxes		(2,166)	(515)		(2,523)
Income tax benefit	[2]	550	150		656
Net of tax		(1,616)	(365)		(1,867)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated (Gain) Loss from Commodity Contracts Cash Flows Hedges [Member]
Amortization of defined benefit pension and postretirement plan items:
Total before income taxes		6,651	2,428		3,623
Income tax benefit	[2]	(1,838)	(671)		(1,028)
Net of tax		4,813	1,757		2,595
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated (Gain) Loss from Interest Rate Swap Cash Flows Hedges
Amortization of defined benefit pension and postretirement plan items:
Total before income taxes		(28)	60
Income tax benefit	[2]		(16)
Net of tax		(28)	44
Other Comprehensive Income Loss Adjustments AOCI Swap Agreements		(28)	60
Propane Swap Agreement [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated (Gain) Loss from Commodity Contracts Cash Flows Hedges [Member]
Amortization of defined benefit pension and postretirement plan items:
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax	[3]	6,651	2,428		1,520
Natural Gas Futures [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated (Gain) Loss from Commodity Contracts Cash Flows Hedges [Member]
Amortization of defined benefit pension and postretirement plan items:
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax	[3],[4]	0	0		2,096
Natural Gas Swaps [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated (Gain) Loss from Commodity Contracts Cash Flows Hedges [Member]
Amortization of defined benefit pension and postretirement plan items:
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax	[3],[4]	$ 0	$ 0		$ 7

[1] 1) These amounts are included in the computation of net periodic benefits. See Note 17, Employee Benefit Plans, for additional details.

[2] (4) The income tax benefit is included in income tax expense in the accompanying consolidated statements of income.

[3] 2) These amounts are included in the effects of gains and losses from derivative instruments. See Note 8, Derivative Instruments, for additional details.

[4] (3) PESCO's results are reflected as discontinued operations in our consolidated statements of income.