Consolidated Statements of Income and Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Change in net unrealized gain (loss) on securities available for sale, tax	$ 4,611	$ 12,868
Change in pension and post-retirement obligations, tax	19	16
Cash flow hedge, gain (loss), reclassification, tax	13,397	13,397
Reclassification adjustment for sales of available-for-sale securities, tax	206	1,517
Cash flow hedges tax component	178	178
Reclassification adjustment for defined benefit pension plan, net of tax	$ 487	$ 695

Amount of tax expense (benefit) before reclassification adjustments of unrealized holding gain (loss) on available-for-sale securities and unrealized holding gain (loss) related to transfers of securities into the available-for-sale category and out of the held-to-maturity category.

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Amount of tax expense (benefit) for reclassification of gain (loss) from accumulated other comprehensive income (AOCI) for derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

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

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Amount of tax expense (benefit) 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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Amount of tax (expense) benefit for reclassification adjustment from accumulated other comprehensive (income) loss of defined benefit plan.

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Amount of tax expense (benefit) before reclassification adjustments of unrealized holding gain (loss) on available-for-sale securities.

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