Condensed Financial Information - Parent Company Only - Condensed Statements of Cash Flows (Detail) - USD ($) $ in Thousands		12 Months Ended
	Sep. 30, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash Flows from Operating Activities
Net Income		$ 84,740	$ 107,369	$ 95,041
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Long-term debt extinguishment costs	$ 831	0	0	831
Excess tax benefits (deficiencies)		130	69	(89)
Increase in other assets		5,942	(68,863)	36,589
Increase in other liabilities		(5,665)	41,813	(37,389)
Net Cash Provided by Operating Activities		115,605	124,696	95,103
Cash Flows from Investing Activities
Net cash used in acquisition		0	67	0
Net Cash Used in Investing Activities:		(290,572)	(651,861)	(615,290)
Cash Flows from Financing Activities
Cash dividends paid on common stock		(38,071)	(37,334)	(27,119)
Proceeds from issuance of subordinated debt, net		0	0	147,738
Redemption of subordinated debentures, net		0	0	(88,330)
Retirement of restricted stock		(1,550)	(1,956)	(651)
Exercise of stock options		0	0	19
Net Cash Provided by Financing Activities:		259,672	534,585	478,627
Net increase (decrease) in cash and cash equivalents		84,705	7,420	(41,560)
Cash and cash equivalents, beginning of year		235,950	228,530	270,090
Cash and cash equivalents, end of year		320,655	235,950	228,530
Parent Company
Cash Flows from Operating Activities
Net Income		84,740	107,369	95,041
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Amortization of subordinated debt costs		441	487	547
Long-term debt extinguishment costs		0	0	831
Excess tax benefits (deficiencies)		130	69	(89)
Increase in other assets		(2,139)	(1,571)	(1,443)
Increase in other liabilities		113	142	149
Equity in undistributed income of subsidiaries		(43,362)	(60,139)	(49,831)
Net Cash Provided by Operating Activities		39,923	46,357	45,205
Cash Flows from Investing Activities
Contribution to subsidiary		0	0	(65,000)
Net Cash Used in Investing Activities:		0	67	(65,000)
Cash Flows from Financing Activities
Cash dividends paid on common stock		(38,071)	(37,334)	(27,119)
Proceeds from issuance of subordinated debt, net		0	0	147,738
Redemption of subordinated debentures, net		0	0	(88,330)
Retirement of restricted stock		(1,550)	(1,956)	(651)
Exercise of stock options		0	0	19
Net Cash Provided by Financing Activities:		(39,621)	(39,290)	31,657
Net increase (decrease) in cash and cash equivalents		302	7,134	11,862
Cash and cash equivalents, beginning of year		47,362	40,228	28,366
Cash and cash equivalents, end of year		$ 47,664	$ 47,362	$ 40,228