Fair Value - Carrying Amounts and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities held to maturity	$ 607,598	$ 342,537
Deposits	15,113,292	15,087,160
Federal funds purchased and securities sold under repurchase agreements	170,499	238,577
Other borrowings	84,644	91,025
Subordinated notes	123,097	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	1,917,564	2,266,829
Securities held to maturity	607,598	342,537
Deposits	15,113,292	15,087,160
Federal funds purchased and securities sold under repurchase agreements	170,499	238,577
Other borrowings	84,644	91,025
Subordinated notes	123,097	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	1,917,564	2,266,829
Securities held to maturity	594,204	353,511
Deposits	15,100,199	15,084,440
Federal funds purchased and securities sold under repurchase agreements	170,499	238,577
Other borrowings	84,639	91,022
Subordinated notes	121,250	128,438
Junior subordinated debt securities	48,866	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	10,316,974	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	$ 10,259,188	$ 10,123,379