Other Comprehensive Income (Loss) - Reclassifications Out of Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains (losses) on sale of securities	$ 292			$ 4,319			$ (375)	$ 5,357
Income taxes	20,962			(6,281)			12,718	(24,342)
Net of tax	(72,275)	$ 7,370	$ 17,537	20,183	$ 21,941	$ 26,408	(47,368)	68,532
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent \| Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains (losses) on sale of securities	(210)			690			(1,423)	243
Income taxes	52			(164)			350	(57)
Net of tax	$ (158)			$ 526			$ (1,073)	$ 186

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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