Fair Value - Financial Instruments not Required to be Carried at Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Financial assets:
Held-to-maturity investment securities, fair value	$ 3,697,261	$ 3,814,822
Lease and lease commitments excluded
Financing leases	332,400	298,100
Deposit liabilities with no defined or contractual maturity	17,800,000	19,200,000
Book Value
Financial assets:
Cash and cash equivalents	558,131	526,624
Held-to-maturity investment securities, fair value	4,180,408	4,320,639
Loans	14,030,432	13,793,922
Financial liabilities:
Time deposits	3,307,772	2,476,050
Short-term borrowings		75,000
Long-term borrowings	500,000
Estimated Fair Value
Financial assets:
Cash and cash equivalents	558,131	526,624
Held-to-maturity investment securities, fair value	3,697,261	3,814,822
Loans	13,304,749	13,138,787
Financial liabilities:
Time deposits	3,262,608	2,423,231
Short-term borrowings		74,991
Long-term borrowings	492,616
Estimated Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets:
Cash and cash equivalents	318,333	297,502
Estimated Fair Value | Significant Other Observable Inputs (Level 2)
Financial assets:
Cash and cash equivalents	239,798	229,122
Held-to-maturity investment securities, fair value	3,697,261	3,814,822
Financial liabilities:
Time deposits	3,262,608	2,423,231
Short-term borrowings		74,991
Long-term borrowings	492,616
Estimated Fair Value | Significant Unobservable Inputs (Level 3)
Financial assets:
Loans	$ 13,304,749	$ 13,138,787