Changes in Accumulated Other Comprehensive Income (Loss) By Component (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ 1,377,406	$ 1,188,721	$ 1,366,217	$ 1,117,086
Unrealized gains (losses) arising during period, before tax	(88,224)	598	(167,082)	13,313
Income tax effect	22,938	(156)	43,441	(3,462)
Other comprehensive income (loss) before reclassifications	(65,286)	442	(123,641)	9,851
Reclassification adjustments for (gains) losses included in net income, before tax	3,991	(766)	5,054	1,594
Income tax effect	(1,038)	199	(1,314)	(415)
Amounts reclassified from accumulated other comprehensive income (loss) to net income	2,953	(567)	3,740	1,179
Other comprehensive income (loss), net of income tax effect	(62,333)	(125)	(119,901)	11,030
Ending balance	1,353,390	1,250,729	1,353,390	1,250,729
Total
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(62,548)	5,391	(4,980)	(5,764)
Other comprehensive income (loss), net of income tax effect	(62,333)	(125)	(119,901)	11,030
Ending balance	(124,881)	5,266	(124,881)	5,266
Unrealized Gains (Losses) on Available for Sale Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(62,548)	6,169	(4,980)	23,312
Unrealized gains (losses) arising during period, before tax	(88,224)	592	(167,082)	992
Income tax effect	22,938	(154)	43,441	(258)
Other comprehensive income (loss) before reclassifications	(65,286)	438	(123,641)	734
Reclassification adjustments for (gains) losses included in net income, before tax	3,991	(1,812)	5,054	(25,378)
Income tax effect	(1,038)	471	(1,314)	6,598
Amounts reclassified from accumulated other comprehensive income (loss) to net income	2,953	(1,341)	3,740	(18,780)
Other comprehensive income (loss), net of income tax effect	(62,333)	(903)	(119,901)	(18,046)
Ending balance	(124,881)	5,266	(124,881)	5,266
Unrealized Gains (Losses) on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	0	(778)	0	(29,076)
Unrealized gains (losses) arising during period, before tax	0	6	0	12,321
Income tax effect	0	(2)	0	(3,204)
Other comprehensive income (loss) before reclassifications	0	4	0	9,117
Reclassification adjustments for (gains) losses included in net income, before tax	0	1,046	0	26,972
Income tax effect	0	(272)	0	(7,013)
Amounts reclassified from accumulated other comprehensive income (loss) to net income	0	774	0	19,959
Other comprehensive income (loss), net of income tax effect	0	778	0	29,076
Ending balance	$ 0	$ 0	$ 0	$ 0

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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