Loans and the Allowance for Credit Losses - Summary of Commercial Loans by Risk Grade (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	$ 11,638,461	$ 10,702,728
Commercial and Industrial [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	1,670,659	1,579,395
Commercial and Industrial [Member] | Pass [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	1,586,683	1,538,300
Commercial and Industrial [Member] | Criticized [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	73,204	25,223
Commercial and Industrial [Member] | Classified - substandard [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	10,772	15,872
Commercial Portfolio Segment [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	8,236,107	7,640,739
Commercial Portfolio Segment [Member] | Pass [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	7,977,436	7,390,239
Commercial Portfolio Segment [Member] | Criticized [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	183,174	147,945
Commercial Portfolio Segment [Member] | Classified - substandard [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	75,497	102,555
Commercial Portfolio Segment [Member] | Commercial Real Estate - Land and Construction [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	1,055,865	943,887
Commercial Portfolio Segment [Member] | Commercial Real Estate - Land and Construction [Member] | Pass [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	1,053,359	911,804
Commercial Portfolio Segment [Member] | Commercial Real Estate - Land and Construction [Member] | Criticized [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	2,497	1,329
Commercial Portfolio Segment [Member] | Commercial Real Estate - Land and Construction [Member] | Classified - substandard [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	9	30,754
Commercial Portfolio Segment [Member] | Commercial Real Estate - Improved Property [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	5,509,583	5,117,457
Commercial Portfolio Segment [Member] | Commercial Real Estate - Improved Property [Member] | Pass [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	5,337,394	4,940,135
Commercial Portfolio Segment [Member] | Commercial Real Estate - Improved Property [Member] | Criticized [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	107,473	121,393
Commercial Portfolio Segment [Member] | Commercial Real Estate - Improved Property [Member] | Classified - substandard [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	64,716	55,929
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	1,670,659	1,579,395
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] | Pass [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	1,586,683	1,538,300
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] | Criticized [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	73,204	25,223
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] | Classified - substandard [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	$ 10,772	$ 15,872