Note 15 - Pension and Other Postretirement Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2021

Notes Tables

Schedule of Changes in Accumulated Postemployment Benefit Obligations [Table Text Block]

	Pension Benefits						Other Postretirement Benefits
	at December 31,						at December 31,
	2021			2020			2021			2020
Change in benefit obligation:
Benefit obligation at beginning of period	$	778,868		$	720,098		$	413,710		$	464,329
Service cost		1,114			1,183			—			—
Interest cost		14,230			20,176			7,274			12,795
Actuarial (gain) loss		(25,073	)		84,663			(42,836	)		(38,455	)
Plan settlement		(719	)		—			—			—
Benefits and other payments		(45,414	)		(47,252	)		(24,851	)		(24,959	)
Benefit obligation at end of period	$	723,006		$	778,868		$	353,297		$	413,710
Change in plan assets:
Fair value of plan assets at beginning of period	$	740,978		$	668,481		$	—		$	—
Actual return on plan assets		36,867			118,403			—			—
Company contributions		2,254			1,346			24,851			24,959
Benefits and other payments		(45,414	)		(47,252	)		(24,851	)		(24,959	)
Plan settlement		(719	)		—			—			—
Fair value of plan assets at end of period	$	733,966		$	740,978		$	—		$	—
Funded status:
Noncurrent assets	$	38,947		$	—		$	—		$	—
Current liabilities		(1,974	)		(2,531	)		(23,638	)		(26,073	)
Noncurrent liabilities		(26,013	)		(35,359	)		(329,659	)		(387,637	)
Net asset (obligation) recognized	$	10,960		$	(37,890	)	$	(353,297	)	$	(413,710	)
Amounts recognized in accumulated other comprehensive loss consist of:
Net actuarial loss	$	231,726		$	256,988		$	82,851		$	132,203
Prior service credit		—			—			(16,138	)		(18,544	)
Net amount recognized (before tax effect)	$	231,726		$	256,988		$	66,713		$	113,659

Schedule of Net Benefit Costs [Table Text Block]

	Pension Benefits									Other Postretirement Benefits
	For the Years Ended December 31,									For the Years Ended December 31,
	2021			2020			2019			2021			2020			2019
Components of net periodic benefit (credit) cost:
Service cost	$	1,114		$	1,183		$	3,950		$	—		$	—		$	—
Interest cost		14,230			20,176			25,101			7,274			12,795			18,320
Expected return on plan assets		(42,168	)		(41,821	)		(40,457	)		—			—			—
Amortization of prior service credits		—			—			(367	)		(2,405	)		(2,405	)		(2,405	)
Recognized net actuarial loss		5,469			6,922			5,958			6,516			9,277			9,262
Settlement loss recognized		22			—			—			—			—			—
Net periodic benefit (credit) cost	$	(21,333	)	$	(13,540	)	$	(5,815	)	$	11,385		$	19,667		$	25,177

Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets [Table Text Block]

	As of December 31,
	2021		2020
Projected benefit obligation	$	27,988	$	778,868
Accumulated benefit obligation	$	27,734	$	778,618
Fair value of plan assets	$	—	$	740,978

Defined Benefit Plan, Assumptions [Table Text Block]

	Pension Obligations						Other Postretirement Obligations
	at December 31,						at December 31,
	2021			2020			2021			2020
Discount rate		2.83	%		2.36	%		2.79	%		2.39	%
Rate of compensation increase		3.78	%		3.76	%		—			—

	Pension Benefits									Other Postretirement Benefits
	For the Years Ended									For the Years Ended
	December 31,									December 31,
	2021			2020			2019			2021			2020			2019
Discount rate		2.46	%		3.35	%		4.37	%		2.39	%		3.27	%		4.34	%
Expected long-term return on plan assets		5.60	%		6.48	%		6.90	%		—			—			—
Rate of compensation increase		3.76	%		3.68	%		3.73	%		—			—			—

Schedule of Health Care Cost Trend Rates [Table Text Block]

	At December 31,
	2021			2020
Health care cost trend rate for next year		5.35	%		5.43	%
Rate to which the cost trend is assumed to decline (ultimate trend rate)		4.00	%		4.50	%
Year that the rate reaches ultimate trend rate	2046			2038

Schedule of Allocation of Plan Assets [Table Text Block]

	Fair Value Measurements at December 31, 2021								Fair Value Measurements at December 31, 2020
			Quoted								Quoted
			Prices in								Prices in
			Active								Active
			Markets for		Significant		Significant				Markets for		Significant		Significant
			Identical		Observable		Unobservable				Identical		Observable		Unobservable
			Assets		Inputs		Inputs				Assets		Inputs		Inputs
	Total		(Level 1)		(Level 2)		(Level 3)		Total		(Level 1)		(Level 2)		(Level 3)
Asset Category
Cash/Accrued Income	$	102	$	102	$	—	$	—	$	100	$	100	$	—	$	—
Mercer Common Collective Trusts (a)		733,864		—		—		—		740,878		—		—		—
Total	$	733,966	$	102	$	—	$	—	$	740,978	$	100	$	—	$	—

Schedule of Expected Benefit Payments [Table Text Block]

			Other
	Pension		Postretirement
	Benefits		Benefits
2022	$	43,826	$	23,638
2023	$	44,331	$	22,893
2024	$	42,723	$	22,063
2025	$	41,253	$	21,810
2026	$	42,622	$	21,460
Year 2027-2031	$	193,244	$	101,663