Retirement Plans and Postretirement Medical Benefits (Fair Value Measurements of Plan Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 5,615	$ 10,416
United States | Total plan assets at fair value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,153,490	1,161,361
United States | Total plan assets at fair value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	170,540	114,084
United States | Total plan assets at fair value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,064,741	1,057,547
United States | Total plan assets at fair value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	67,256	91,500
United States | Total plan assets at fair value | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,302,537	1,263,131
United States | Money market funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Money market funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	13,842	10,623
United States | Money market funds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Money market funds | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	13,842	10,623
United States | Equities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Equities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	102,795	137,505
United States | Equities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Equities | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	102,795	137,505
United States | Commingled fixed income securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Commingled fixed income securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	220,041	220,281
United States | Commingled fixed income securities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Commingled fixed income securities | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	220,041	220,281
United States | Government and related securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	170,540	114,084
United States | Government and related securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	28,518	21,479
United States | Government and related securities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Government and related securities | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	199,058	135,563
United States | Corporate debt securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Corporate debt securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	545,615	527,407
United States | Corporate debt securities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Corporate debt securities | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	545,615	527,407
United States | Mortgage-backed /asset-backed securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Mortgage-backed /asset-backed securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	49,300	26,450
United States | Mortgage-backed /asset-backed securities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Mortgage-backed /asset-backed securities | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	49,300	26,450
United States | Real estate | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Real estate | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Real estate | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	67,256	91,500
United States | Real estate | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	67,256	91,500
United States | Securities lending collateral | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Securities lending collateral | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	104,630	113,802
United States | Securities lending collateral | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Securities lending collateral | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	104,630	113,802
United States | Securities lending payable
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	104,630	113,802
United States | Cash
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,240	3,525
United States | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	51,272	1,909
Foreign | Total plan assets at fair value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	466,687	438,403
Foreign | Total plan assets at fair value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Foreign | Total plan assets at fair value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	416,476	365,061
Foreign | Total plan assets at fair value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	43,205	67,374
Foreign | Total plan assets at fair value | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	459,681	432,435
Foreign | Money market funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Foreign | Money market funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,997	8,338
Foreign | Money market funds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Foreign | Money market funds | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,997	8,338
Foreign | Equities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Foreign | Equities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	44,088	42,717
Foreign | Equities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Foreign | Equities | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	44,088	42,717
Foreign | Commingled fixed income securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Foreign | Commingled fixed income securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	295,105	247,337
Foreign | Commingled fixed income securities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Foreign | Commingled fixed income securities | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	295,105	247,337
Foreign | Government and related securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Foreign | Government and related securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	38,028	35,887
Foreign | Government and related securities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Foreign | Government and related securities | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	38,028	35,887
Foreign | Corporate debt securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Foreign | Corporate debt securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	28,389	26,336
Foreign | Corporate debt securities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Foreign | Corporate debt securities | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	28,389	26,336
Foreign | Real estate
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	43,205	42,980	$ 52,491
Foreign | Real estate | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Foreign | Real estate | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,869	4,446
Foreign | Real estate | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	43,205	42,980
Foreign | Real estate | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	48,074	47,426
Foreign | Diversified growth funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	24,394	$ 52,169
Foreign | Diversified growth funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Foreign | Diversified growth funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Foreign | Diversified growth funds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	24,394
Foreign | Diversified growth funds | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	24,394
Foreign | Cash
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6,501	5,485
Foreign | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 505	$ 483