TAX EFFECT ALLOCATED TO EACH COMPONENT OF OTHER COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Statement of Income and Comprehensive Income
Amortization of net losses of pension and postretirement benefit plans	$ (1,948)	$ (2,011)
Unrealized holding (losses) gains on debt securities arising during the period	27,382	(65,341)
Unrealized net gains (losses) on cash flow hedges	(866)	1,113
Reclassification adjustment for net (gains) losses included in net income	139	(486)
Income tax benefit (expense)	$ 24,707	$ (66,725)

Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income of accumulated gain (loss) realized from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's deferred hedging gain (loss).

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

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

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Amount of tax expense (benefit), before reclassification adjustments, related to increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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Amount, before adjustment, of tax expense (benefit) for unrealized holding gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Excludes tax expense (benefit) for unrealized gain (loss) on investment in debt security measured at amortized cost (held-to-maturity) from transfer to available-for-sale.

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