Consolidated Condensed Statements of Shareholders' Equity (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement Of Stockholders Equity [Abstract]
Tax effect on employee benefit funded status adjustment	$ 4	$ (4)	$ 3	$ 133
Cash dividends (in dollars per share)	$ 0.18	$ 0.17	$ 0.52	$ 0.47
Issuance of treasury stock (in shares)	21	21	42	49

Amount, after reclassification adjustment, of tax (expense) benefit for (increase) decrease in accumulated other comprehensive income for defined benefit plan, attributable to parent.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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