Fair Value - Carrying Amounts and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities held to maturity	$ 1,137,754	$ 342,537
Deposits	14,770,168	15,087,160
Federal funds purchased and securities sold under repurchase agreements	70,157	238,577
Other borrowings	72,553	91,025
Subordinated notes	123,152	123,042
Junior subordinated debt securities	61,856	61,856
Level 2 [Member] | Carrying Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and short-term investments	742,461	2,266,829
Securities held to maturity	1,137,754	342,537
Deposits	14,770,168	15,087,160
Federal funds purchased and securities sold under repurchase agreements	70,157	238,577
Other borrowings	72,553	91,025
Subordinated notes	123,152	123,042
Junior subordinated debt securities	61,856	61,856
Level 2 [Member] | Estimate Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and short-term investments	742,461	2,266,829
Securities held to maturity	1,102,459	353,511
Deposits	14,749,561	15,084,440
Federal funds purchased and securities sold under repurchase agreements	70,157	238,577
Other borrowings	72,547	91,022
Subordinated notes	117,813	128,438
Junior subordinated debt securities	48,248	49,485
Level 3 [Member] | Carrying Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net LHFI and PPP loans	10,854,249	10,181,708
Level 3 [Member] | Estimate Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net LHFI and PPP loans	$ 10,746,795	$ 10,123,379