Employee Benefit Plans - Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net periodic benefit cost [Abstract]
Settlement & curtailment (gain) loss	$ (9,926)	$ 2,462	$ 0
Total net periodic benefit cost	11,912	12,191	25,364
Supplemental Employee Retirement Plans, Defined Benefit [Member]
Net periodic benefit cost [Abstract]
Amortization of prior service costs (income)	3,770	4,411	6,266
Amortization of actuarial (gains) losses	(1,132)	(1,192)	(560)
Settlement & curtailment (gain) loss	(1,381)	0	0
Defined Benefit Plan, Other Cost (Credit)	0	0	0
Total net periodic benefit cost	7,085	9,768	13,933
Supplemental Employee Retirement Plans, Defined Benefit [Member] | Nonqualified Plan [Member]
Net periodic benefit cost [Abstract]
Service cost	2,624	2,473	2,959
Interest cost	3,204	4,076	5,268
Expected return on plan assets	0	0	0
Other Postretirement Benefit Plans, Defined Benefit [Member]
Net periodic benefit cost [Abstract]
Service cost	30	68	52
Interest cost	290	783	403
Amortization of prior service costs (income)	13	7	7
Amortization of actuarial (gains) losses	(30)	(161)	5
Settlement & curtailment (gain) loss	0	(4,598)	0
Total net periodic benefit cost	303	(3,901)	467
Domestic Plan [Member] | Pension Plan [Member] | Qualified Plan [Member]
Net periodic benefit cost [Abstract]
Service cost	9,019	12,083	13,913
Interest cost	20,756	21,718	23,046
Expected return on plan assets	(39,045)	(39,812)	(38,793)
Amortization of prior service costs (income)	298	427	733
Amortization of actuarial (gains) losses	3,102	5,582	6,437
Amortization of transition obligation	0	0	0
Settlement & curtailment (gain) loss	13,939	76	0
Defined Benefit Plan, Other Cost (Credit)	0	0	35
Total net periodic benefit cost	8,069	74	5,371
Foreign Plan [Member] | Pension Plan [Member] | Qualified Plan [Member]
Net periodic benefit cost [Abstract]
Service cost	5,359	5,688	5,590
Interest cost	4,962	5,263	5,593
Expected return on plan assets	(7,675)	(7,417)	(7,830)
Amortization of prior service costs (income)	(449)	(425)	(397)
Amortization of actuarial (gains) losses	2,952	3,506	2,658
Amortization of transition obligation	(1)	(4)	(4)
Settlement & curtailment (gain) loss	7	678	1,103
Defined Benefit Plan, Other Cost (Credit)	0	0	0
Total net periodic benefit cost	5,157	7,297	6,721
Continuing Operations [Member] | Supplemental Employee Retirement Plans, Defined Benefit [Member] | Nonqualified Plan [Member]
Net periodic benefit cost [Abstract]
Total net periodic benefit cost	6,806	8,542	12,711
Continuing Operations [Member] | Domestic Plan [Member] | Pension Plan [Member] | Qualified Plan [Member]
Net periodic benefit cost [Abstract]
Total net periodic benefit cost	(2,040)	(3,309)	1,134
Continuing Operations [Member] | Foreign Plan [Member] | Pension Plan [Member] | Qualified Plan [Member]
Net periodic benefit cost [Abstract]
Total net periodic benefit cost	5,043	6,487	5,747
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	279	1,226	1,222
Discontinued Operations [Member] | Domestic Plan [Member] | Pension Plan [Member] | Qualified Plan [Member]
Net periodic benefit cost [Abstract]
Total net periodic benefit cost	10,109	3,383	4,237
Discontinued Operations [Member] | Foreign Plan [Member] | Pension Plan [Member] | Qualified Plan [Member]
Net periodic benefit cost [Abstract]
Total net periodic benefit cost	$ 114	$ 810	$ 974