Goodwill and Other Intangibles - Summary of Goodwill and Other Intangible Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Balances not subject to amortization
Goodwill	$ 640,222	$ 640,222
Balances subject to amortization
Total other intangible assets	18,771	20,904
Total goodwill and other intangible assets	658,993	661,126
Insurance agency
Balances subject to amortization
Balances subject to amortization	9,193	10,530
Core deposit intangible (2)
Balances subject to amortization
Balances subject to amortization	$ 9,578	10,374
Remaining useful life of intangible	5 years
Banking Business
Balances not subject to amortization
Goodwill	$ 557,635	557,635
Balances subject to amortization
Total other intangible assets	9,578	10,374
Total goodwill and other intangible assets	567,213	568,009
Banking Business | Insurance agency
Balances subject to amortization
Balances subject to amortization	0	0
Banking Business | Core deposit intangible (2)
Balances subject to amortization
Balances subject to amortization	9,578	10,374
Insurance Agency Business
Balances not subject to amortization
Goodwill	82,587	82,587
Balances subject to amortization
Total other intangible assets	9,193	10,530
Total goodwill and other intangible assets	91,780	93,117
Insurance Agency Business | Insurance agency
Balances subject to amortization
Balances subject to amortization	9,193	10,530
Insurance Agency Business | Core deposit intangible (2)
Balances subject to amortization
Balances subject to amortization	$ 0	$ 0