Goodwill and Other Intangibles - Summary of Goodwill and Other Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Balances not subject to amortization
Goodwill	$ 640,222	$ 631,496
Balances subject to amortization
Total other intangible assets	22,000	18,207
Total goodwill and other intangible assets	662,222	649,703
Insurance agency
Balances subject to amortization
Balances subject to amortization	11,327	6,635
Core deposit intangible
Balances subject to amortization
Balances subject to amortization	10,673	11,572
Banking Business
Balances not subject to amortization
Goodwill	557,635	557,635
Balances subject to amortization
Total other intangible assets	10,673	11,572
Total goodwill and other intangible assets	568,308	569,207
Banking Business | Insurance agency
Balances subject to amortization
Balances subject to amortization	0	0
Banking Business | Core deposit intangible
Balances subject to amortization
Balances subject to amortization	10,673	11,572
Insurance Agency Business
Balances not subject to amortization
Goodwill	82,587	73,861
Balances subject to amortization
Total other intangible assets	11,327	6,635
Total goodwill and other intangible assets	93,914	80,496
Insurance Agency Business | Insurance agency
Balances subject to amortization
Balances subject to amortization	11,327	6,635
Insurance Agency Business | Core deposit intangible
Balances subject to amortization
Balances subject to amortization	$ 0	$ 0