Employee and Retiree Benefit Plans - Fair Value Measurements of Retirement Plan Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	$ 586,720	$ 547,484
Level 1
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	124,407	102,651
Level 2
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	364,628	333,247
Level 3
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	97,685	111,586
U.S.
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	365,257	349,519
U.S. | Level 1
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	124,407	102,651
U.S. | Level 2
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	179,135	170,943
U.S. | Level 3
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	61,715	75,925
U.S. | U.S. core equity
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	67,326	63,169
U.S. | U.S. core equity | Level 1
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	67,326	63,169
U.S. | U.S. core equity | Level 2
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	0	0
U.S. | U.S. core equity | Level 3
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	0	0
U.S. | U.S. small/midcap
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	28,953	26,062
U.S. | U.S. small/midcap | Level 1
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	28,953	26,062
U.S. | U.S. small/midcap | Level 2
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	0	0
U.S. | U.S. small/midcap | Level 3
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	0	0
U.S. | Hedged funds and other alternative strategies
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	42,040	58,864
U.S. | Hedged funds and other alternative strategies | Level 1
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	0	0
U.S. | Hedged funds and other alternative strategies | Level 2
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	0	0
U.S. | Hedged funds and other alternative strategies | Level 3
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	42,040	58,864
U.S. | International commingled trust fund
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	76,095	73,783
U.S. | International commingled trust fund | Level 1
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	987	924
U.S. | International commingled trust fund | Level 2
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	55,433	55,798
U.S. | International commingled trust fund | Level 3
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	19,675	17,061
U.S. | Emerging market commingled equity fund
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	32,058	25,911
U.S. | Emerging market commingled equity fund | Level 1
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	10,480	8,011
U.S. | Emerging market commingled equity fund | Level 2
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	21,578	17,900
U.S. | Emerging market commingled equity fund | Level 3
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	0	0
U.S. | U.S. fixed income
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	92,668	88,525
U.S. | U.S. fixed income | Level 1
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	0	0
U.S. | U.S. fixed income | Level 2
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	92,668	88,525
U.S. | U.S. fixed income | Level 3
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	0	0
U.S. | International commingled trust fund
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	9,456	8,720
U.S. | International commingled trust fund | Level 1
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	0	0
U.S. | International commingled trust fund | Level 2
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	9,456	8,720
U.S. | International commingled trust fund | Level 3
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	0	0
U.S. | Cash and equivalents
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	16,661	4,485
U.S. | Cash and equivalents | Level 1
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	16,661	4,485
U.S. | Cash and equivalents | Level 2
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	0	0
U.S. | Cash and equivalents | Level 3
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	0	0
Foreign Plans
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	221,463	197,965
Foreign Plans | Level 1
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	0	0
Foreign Plans | Level 2
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	185,493	162,304
Foreign Plans | Level 3
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	35,970	35,661
Foreign Plans | Cash and equivalents
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	10,989	4,262
Foreign Plans | Cash and equivalents | Level 1
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	0	0
Foreign Plans | Cash and equivalents | Level 2
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	10,989	4,262
Foreign Plans | Cash and equivalents | Level 3
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	0	0
Foreign Plans | Equity securities funds
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	74,393	68,878
Foreign Plans | Equity securities funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	0	0
Foreign Plans | Equity securities funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	74,393	68,878
Foreign Plans | Equity securities funds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	0	0
Foreign Plans | Fixed income securities funds
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	45,240	46,582
Foreign Plans | Fixed income securities funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	0	0
Foreign Plans | Fixed income securities funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	45,240	46,582
Foreign Plans | Fixed income securities funds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	0	0
Foreign Plans | Diversified pooled fund
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	54,871	42,582
Foreign Plans | Diversified pooled fund | Level 1
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	0	0
Foreign Plans | Diversified pooled fund | Level 2
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	54,871	42,582
Foreign Plans | Diversified pooled fund | Level 3
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	0	0
Foreign Plans | Other
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	35,970	35,661
Foreign Plans | Other | Level 1
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	0	0
Foreign Plans | Other | Level 2
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	0	0
Foreign Plans | Other | Level 3
Defined Benefit Plan Disclosure [Line Items]
Retirement plan assets	$ 35,970	$ 35,661