Changes in Accumulated Other Comprehensive Income (Loss) By Component (Detail) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2023	Mar. 31, 2022
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ 1,402,961	$ 1,366,217
Amortization of unrealized loss on securities transferred from available-for-sale to held-to-maturity	872	0
Income tax effect	(221)	0
Other comprehensive income (loss), net of income tax effect	6,820	(57,568)
Ending balance	1,421,020	1,377,406
Total
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(163,096)	(4,980)
Other comprehensive income (loss), net of income tax effect	6,820	(57,568)
Ending balance	(156,276)	(62,548)
Unrealized Gains (Losses) on Available for Sale Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(163,096)	(4,980)
Unrealized gains (losses) arising during period, before tax	8,270	(78,858)
Income tax effect	(2,101)	20,503
Other comprehensive income (loss) before reclassifications	6,169	(58,355)
Reclassification adjustments for (gains) losses included in net income, before tax	0	1,063
Income tax effect	0	(276)
Amounts reclassified from accumulated other comprehensive income (loss) to net income	0	787
Amortization of unrealized loss on securities transferred from available-for-sale to held-to-maturity	872	0
Income tax effect	(221)	0
Amortization of unrealized loss on securities transferred from available for sale to held to maturity	651	0
Other comprehensive income (loss), net of income tax effect	6,820	(57,568)
Ending balance	$ (156,276)	$ (62,548)

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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