Loans and the Allowance for Credit Losses - Summary of Commercial Loans by Risk Grade (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	$ 12,257,511	$ 11,638,461
Commercial and Industrial [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	1,760,479	1,670,659
Commercial and Industrial [Member] | Pass [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	1,681,579	1,586,683
Commercial and Industrial [Member] | Criticized [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	70,056	73,204
Commercial and Industrial [Member] | Classified - substandard [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	8,844	10,772
Commercial Portfolio Segment [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	8,759,367	8,236,107
Commercial Portfolio Segment [Member] | Pass [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	8,496,002	7,977,436
Commercial Portfolio Segment [Member] | Criticized [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	179,621	183,174
Commercial Portfolio Segment [Member] | Classified - substandard [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	83,744	75,497
Commercial Portfolio Segment [Member] | Commercial Real Estate - Land and Construction [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	1,061,390	1,055,865
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	1,058,739	1,053,359
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	972	2,497
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	1,679	9
Commercial Portfolio Segment [Member] | Commercial Real Estate - Improved Property [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	5,937,498	5,509,583
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	5,755,684	5,337,394
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	108,593	107,473
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	73,221	64,716
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	1,760,479	1,670,659
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] | Pass [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	1,681,579	1,586,683
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] | Criticized [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	70,056	73,204
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] | Classified - substandard [Member]
Summary of commercial loans by risk grade
Portfolio loans, net of unearned income	$ 8,844	$ 10,772