A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

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- Definition

Amount before tax and reclassification adjustments of other comprehensive income (loss).

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- Definition

Amount after tax and reclassification adjustments of other comprehensive income (loss).

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- Definition

Amount of tax expense (benefit) allocated to other comprehensive income (loss).

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- Definition

Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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- Definition

Amount of increase (decrease) in accumulated other comprehensive income (AOCI) for reclassification to retained earnings of tax effect from remeasurement of deferred tax pursuant to Tax Cuts and Jobs Act.

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Other Comprehensive Income (Loss), Summary of Unrealized Gains and Losses on Postretirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Balance	$ 208,489	$ 204,593	$ 197,787	$ 191,542	$ 184,661	$ 183,304	$ 181,372	$ 181,321	$ 191,542	$ 181,321	$ 172,521
Reclassification adjustment for effect of enacted tax law changes											0
Other comprehensive gain (loss)	327	597	3,395	3,050	3,419	(1,677)	(904)	(2,933)	7,369	(2,095)	(1,378)
Balance	212,508	$ 208,489	$ 204,593	197,787	191,542	$ 184,661	$ 183,304	181,372	212,508	191,542	181,321
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss)
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Balance				$ 37				$ (147)	37	(147)	(102)
Unrealized gains (losses) during the period									(16)	233	(30)
Related deferred taxes									3	(49)	11
Reclassification adjustment for effect of enacted tax law changes									0	0	(26)
Other comprehensive gain (loss)									(13)	184	(45)
Balance	$ 24				$ 37				$ 24	$ 37	$ (147)