Consolidated Condensed Statements of Shareholders' Equity (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement Of Stockholders Equity [Abstract]
Tax effect on employee benefit funded status adjustment	$ 1	$ 1	$ 2	$ 1
Cash dividends (in dollars per share)	$ 0.18	$ 0.17	$ 0.36	$ 0.34
Issuance of treasury stock (in shares)	23	6	46	15

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
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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