Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 23,297	$ 25,019	$ 57,829	$ 71,163
Unrealized gains (losses) on securities available for sale:
Unrealized holding gains (losses) arising during the period, pretax	19	2,210	23,556	19,814
Tax (expense) benefit	(4)	(508)	(5,413)	(4,602)
Reclassification to realized (gains) losses	0	(97)	(8,024)	(97)
Tax expense (benefit)	0	22	1,844	22
Postretirement Plans:
Amortization of unrecognized net actuarial loss	153	155	511	611
Tax benefit	(35)	(36)	(118)	(153)
Other comprehensive income (loss)	133	1,746	12,356	15,595
Comprehensive income	$ 23,430	$ 26,765	$ 70,185	$ 86,758

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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