Employee Benefit Plans - Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net periodic benefit cost [Abstract]
Settlement & curtailment (gain) loss	$ (806)	$ (9,926)	$ 2,462
Total net periodic benefit cost	5,844	11,912	12,191
Supplemental Employee Retirement Plans, Defined Benefit [Member]
Net periodic benefit cost [Abstract]
Amortization of prior service costs (income)			4,411
Amortization of actuarial (gains) losses			1,192
Settlement & curtailment (gain) loss	0	1,381	0
Total net periodic benefit cost	5,143	7,085	9,768
Supplemental Employee Retirement Plans, Defined Benefit [Member] | Nonqualified Plan [Member]
Net periodic benefit cost [Abstract]
Service cost	1,942	2,624	2,473
Interest cost	2,670	3,204	4,076
Expected return on plan assets	0	0	0
Amortization of prior service costs (income)	2,811	3,770
Amortization of actuarial (gains) losses	2,280	1,132
Other Postretirement Benefit Plans, Defined Benefit [Member]
Net periodic benefit cost [Abstract]
Service cost	19	30	68
Interest cost	312	290	783
Amortization of prior service costs (income)	13	13	7
Amortization of actuarial (gains) losses	(70)	(30)	(161)
Settlement & curtailment (gain) loss	0	0	(4,598)
Total net periodic benefit cost	274	303	(3,901)
United States | Pension Plan [Member] | Qualified Plan [Member]
Net periodic benefit cost [Abstract]
Service cost	7,016	9,019	12,083
Interest cost	19,026	20,756	21,718
Expected return on plan assets	34,136	39,045	39,812
Amortization of prior service costs (income)	303	298	427
Amortization of actuarial (gains) losses	0	3,102	5,582
Amortization of transition obligation	0	0	0
Settlement & curtailment (gain) loss	0	13,939	76
Total net periodic benefit cost	(7,791)	8,069	74
Foreign Plan [Member] | Pension Plan [Member] | Qualified Plan [Member]
Net periodic benefit cost [Abstract]
Service cost	5,665	5,359	5,688
Interest cost	5,101	4,962	5,263
Expected return on plan assets	6,220	7,675	7,417
Amortization of prior service costs (income)	(398)	(449)	(425)
Amortization of actuarial (gains) losses	3,109	2,952	3,506
Amortization of transition obligation	0	(1)	(4)
Settlement & curtailment (gain) loss	961	7	678
Total net periodic benefit cost	8,218	5,157	7,297
Continuing Operations [Member] | Supplemental Employee Retirement Plans, Defined Benefit [Member] | Nonqualified Plan [Member]
Net periodic benefit cost [Abstract]
Total net periodic benefit cost	5,143	6,806	8,542
Continuing Operations [Member] | United States | Pension Plan [Member] | Qualified Plan [Member]
Net periodic benefit cost [Abstract]
Total net periodic benefit cost	(7,791)	(2,040)	(3,309)
Continuing Operations [Member] | Foreign Plan [Member] | Pension Plan [Member] | Qualified Plan [Member]
Net periodic benefit cost [Abstract]
Total net periodic benefit cost	8,218	5,043	6,487
Discontinued Operations [Member]
Net periodic benefit cost [Abstract]
Settlement & curtailment (gain) loss		9,200
Discontinued Operations [Member] | Supplemental Employee Retirement Plans, Defined Benefit [Member] | Nonqualified Plan [Member]
Net periodic benefit cost [Abstract]
Total net periodic benefit cost	0	279	1,226
Discontinued Operations [Member] | United States | Pension Plan [Member] | Qualified Plan [Member]
Net periodic benefit cost [Abstract]
Total net periodic benefit cost	0	10,109	3,383
Discontinued Operations [Member] | Foreign Plan [Member] | Pension Plan [Member] | Qualified Plan [Member]
Net periodic benefit cost [Abstract]
Total net periodic benefit cost	$ 0	$ 114	$ 810