Employee Benefit Plans Unrecognized loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	$ (137)
Unrecognized gains arising in current year	(2,532)	$ (937)	$ 1,400
Ending Balance	65,091	(137)
Amount to be amortized from accumulated other comprehensive income (loss) in next twelve months	2,300
Unrecognized Pension and Postretirement Plan Income (Cost)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	(15,001)	(15,089)	(14,923)
Ending Balance	(16,513)	(15,001)	(15,089)
Pension Plans | Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss) [Member]
Before tax
AOCI before Tax, Attributable to Parent	23,546	24,347
Reclass adjustment for postretirement plan gain included in net income	(1,859)	(1,981)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax	3,787	1,180
AOCI before Tax, Attributable to Parent	25,474	23,546	24,347
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	18,337	18,961
Recognized component of periodic pension cost	(1,452)	(1,543)
Unrecognized gains arising in current year	2,958	919
Ending Balance	19,843	18,337	18,961
Other Postretirement Benefit Plans | Accumulated Defined Benefit Plans Adjustment, Net Prior Service Cost [Member]
Before tax
AOCI before Tax, Attributable to Parent	(3,476)	(3,940)
Reclass adjustment for postretirement plan gain included in net income	464	464
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Prior to Curtailment, before Tax		0
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax	0
AOCI before Tax, Attributable to Parent	(3,012)	(3,476)	(3,940)
Other Postretirement Benefit Plans | Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss) [Member]
Before tax
AOCI before Tax, Attributable to Parent	(948)	(1,096)
Reclass adjustment for postretirement plan gain included in net income	84	92
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Prior to Curtailment, before Tax		56
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax	6
AOCI before Tax, Attributable to Parent	(858)	(948)	(1,096)
Other Postretirement Benefit Plans | Unrecognized Pension and Postretirement Plan Income (Cost)
Before tax
AOCI before Tax, Attributable to Parent	(4,424)	(5,036)
Reclass adjustment for postretirement plan gain included in net income	548	556
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Prior to Curtailment, before Tax		56
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax	6
AOCI before Tax, Attributable to Parent	(3,870)	(4,424)	(5,036)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	(3,451)	(3,928)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Prior to Curtailment, Net of Tax		433
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Prior to Curtailment, Net of Tax		44
Recognized component of periodic pension cost	428
Unrecognized gains arising in current year	5
Ending Balance	$ (3,018)	$ (3,451)	$ (3,928)