Accumulated Other Comprehensive Income Reclassification Out Of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net realized gain (loss) on investment		$ 333	$ 1,340
Prior year service cost		0	0
Unrecognized loss		0	0
Income before Income Taxes		49,661	39,823
Tax		(10,241)	(8,365)
Net income		39,420	31,458
Reclassification Out Of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net income		(347)	0
Reclassification Out Of Accumulated Other Comprehensive Income | Unrealized Gains And Losses On Available-For-Sale Securities
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net realized gain (loss) on investment		30	0
Other-than-temporary impairments		(482)	0
Income before Income Taxes		(452)	0
Tax		105	0
Net income		(347)	0
Reclassification Out Of Accumulated Other Comprehensive Income | Postretirement Benefits Plans
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Prior year service cost		0	0
Unrecognized loss		0	0
Income before Income Taxes	[1]	0	0
Tax		0	0
Net income		$ 0	$ 0

[1] These accumulated other comprehensive income components are not reclassified to net income in their entirety in the same reporting period. The amounts are presented within personnel expenses on the Consolidated Statements of Operations as amortized. Amortization related to postretirement benefit plans is included in the computation of net periodic pension costs, as discussed in Note 10.