Fair Value - Carrying Amounts and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities held to maturity	$ 342,537	$ 538,072
Deposits	15,087,160	14,048,764
Federal funds purchased and securities sold under repurchase agreements	238,577	164,519
Other borrowings	91,025	168,252
Subordinated notes	123,042	122,921
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	2,266,829	1,952,554
Securities held to maturity	342,537	538,072
Deposits	15,087,160	14,048,764
Federal funds purchased and securities sold under repurchase agreements	238,577	164,519
Other borrowings	91,025	168,252
Subordinated notes	123,042	122,921
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	2,266,829	1,952,554
Securities held to maturity	353,511	563,115
Deposits	15,084,440	14,052,863
Federal funds purchased and securities sold under repurchase agreements	238,577	164,519
Other borrowings	91,022	168,252
Subordinated notes	128,438	127,500
Junior subordinated debt securities	49,485	46,083
Level 3 [Member] | Carrying Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net LHFI and PPP loans	10,181,708	10,317,352
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	$ 10,123,379	$ 10,312,395