Consolidated Statements of Income and Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Accumulated other comprehensive income reclassification for change in fair value of interest rate swap agreements	$ 63
Accumulated other comprehensive income reclassification for change in fair value of interest rate swap agreements, before 2017-12 adoption		$ 164	$ 288
Accumulated other comprehensive income reclassifications for net realized gains on available-for-sale securities	148	0	1,543
Accumulated other comprehensive income reclassifications on employee benefits	23	84	192
Income tax expense from reclassification	$ 13	$ (52)	$ 372

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Amount, before tax and reclassification, of gain (loss) from derivative instrument designated and qualifying cash flow hedge included in assessment of hedge effectiveness.

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Amount before tax of reclassification adjustment from accumulated other comprehensive income for unrealized gain (loss) realized upon the sale of available-for-sale securities.

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