Employee Benefit Plans (Funded Status) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Pension Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation	$ 146,882	$ 152,341
Fair value of plan assets	235,297	210,993	$ 247,583
Non-current asset	3,917	1,776
Current liability	(3,998)	(3,494)
Non-current liability	(146,801)	(150,623)
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position	(146,882)	(152,341)
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax	30,872	28,497
Prior service cost	322	325
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax	31,194	28,822
Defined Benefit Plan, Amortization of Net Gains (Losses)	(277)
Prior service cost	16
Defined Benefit Plan, Benefit Obligation	(382,179)	(363,334)	(399,638)
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(146,882)	(152,341)
Defined Benefit Plan, Expected Amortization, Next Fiscal Year	293
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Aggregate accumulated benefit obligation (ABO)	382,179	363,334
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Pension Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation	10,193	10,276
Fair value of plan assets	0	0	0
Non-current asset	0	0
Current liability	(669)	(701)
Non-current liability	(9,524)	(9,575)
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position	(10,193)	(10,276)
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax	(883)	(902)
Defined Benefit Plan, Benefit Obligation	(10,193)	(10,276)	$ (11,685)
Defined Benefit Plan, Funded (Unfunded) Status of Plan	$ (10,193)	$ (10,276)