Stockholders' Equity Accumulated Other Comprehensive Income (loss) - Reclassifications of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Amortization of defined benefit pension and postretirement plan items:
Income tax benefit		$ (33,832)	$ (29,231)	$ (23,538)
Accumulated other comprehensive income (loss)		(1,379)	1,303	(2,865)
Other Comprehensive Income (Loss), before Reclassifications, before Tax		(229)	7,337
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		(2,453)	(3,169)
Other Comprehensive Income (Loss), Net of Tax		(2,682)	4,168
Accumulated (Gain) Loss from Commodity Contracts Cash Flows Hedges [Member]
Amortization of defined benefit pension and postretirement plan items:
Accumulated other comprehensive income (loss)		1,092	4,571	2,309
Other Comprehensive Income (Loss), before Reclassifications, before Tax		(934)	7,075
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		(2,545)	(4,813)	(1,757)
Other Comprehensive Income (Loss), Net of Tax		(3,479)	2,262
Accumulated (Gain) Loss from Interest Rate Swap Cash Flows Hedges
Amortization of defined benefit pension and postretirement plan items:
Accumulated other comprehensive income (loss)		35	0	(28)
Other Comprehensive Income (Loss), before Reclassifications, before Tax		0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax			28
Other Comprehensive Income (Loss), Net of Tax		35	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)		(2,506)	(3,268)	(5,146)
Other Comprehensive Income (Loss), before Reclassifications, before Tax		705	262
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		57	1,616
Other Comprehensive Income (Loss), Net of Tax		762	1,878
Reclassification out of Accumulated Other Comprehensive Income [Member]
Amortization of defined benefit pension and postretirement plan items:
Net of tax		2,453	3,169	1,436
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	[1]	(152)	(2,243)	(592)
Total before income taxes		(75)	(2,166)	(515)
Income tax benefit	[2]	18	550	150
Net of tax		(57)	(1,616)	(365)
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		3,508	6,651	2,428
Income tax benefit	[2]	(963)	(1,838)	(671)
Net of tax		2,545	4,813	1,757
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		(47)	(40)	60
Income tax benefit	[2]	12	12	(16)
Net of tax		(35)	(28)	44
Other Comprehensive Income Loss Adjustments AOCI Swap Agreements		(47)	(40)	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]	$ 3,508	$ 6,651	$ 2,428

[1] 1) These amounts are included in the computation of net periodic benefits. See Note 16, Employee Benefit Plans, for additional details.

[2] (3) 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.