Fair Value Measurements - Assets and liabilities measured at fair value on recurring basis (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Assets:
Debt securities available-for-sale	$ 4,496,824	$ 3,224,721
Mortgage loans held for sale	44,109	105,433
U.S. Treasuries
Assets:
Debt securities available-for-sale	217,520	128,072
U.S. Government agencies & GSEs
Assets:
Debt securities available-for-sale	187,032	152,972
State and political subdivisions
Assets:
Debt securities available-for-sale	275,844	274,472
Corporate bonds
Assets:
Debt securities available-for-sale	193,166	71,767
Asset-backed securities
Assets:
Debt securities available-for-sale	604,277	562,722
Recurring
Assets:
Equity securities with readily determinable fair values	1,302	1,687
Mortgage loans held for sale	44,109	105,433
Deferred compensation plan assets	11,769	9,584
Servicing rights for SBA/USDA loans	6,513	6,462
Residential mortgage servicing rights	25,161	16,216
Derivative financial instruments	42,480	86,666
Total assets	4,628,158	3,450,769
Liabilities:
Deferred compensation plan liability	11,795	9,590
Derivative financial instruments	25,145	29,003
Total liabilities	36,940	38,593
Recurring \| U.S. Treasuries
Assets:
Debt securities available-for-sale	217,520	128,072
Recurring \| U.S. Government agencies & GSEs
Assets:
Debt securities available-for-sale	187,032	152,972
Recurring \| State and political subdivisions
Assets:
Debt securities available-for-sale	275,844	274,472
Recurring \| Residential MBS
Assets:
Debt securities available-for-sale	2,145,134	1,485,585
Recurring \| Commercial MBS
Assets:
Debt securities available-for-sale	873,851	549,131
Recurring \| Corporate bonds
Assets:
Debt securities available-for-sale	193,166	71,767
Recurring \| Asset-backed securities
Assets:
Debt securities available-for-sale	604,277	562,722
Recurring \| Level 1
Assets:
Equity securities with readily determinable fair values	0	774
Mortgage loans held for sale	0	0
Deferred compensation plan assets	11,769	9,584
Servicing rights for SBA/USDA loans	0	0
Residential mortgage servicing rights	0	0
Derivative financial instruments	0	0
Total assets	229,289	138,430
Liabilities:
Deferred compensation plan liability	11,795	9,590
Derivative financial instruments	0	0
Total liabilities	11,795	9,590
Recurring \| Level 1 \| U.S. Treasuries
Assets:
Debt securities available-for-sale	217,520	128,072
Recurring \| Level 1 \| U.S. Government agencies & GSEs
Assets:
Debt securities available-for-sale	0	0
Recurring \| Level 1 \| State and political subdivisions
Assets:
Debt securities available-for-sale	0	0
Recurring \| Level 1 \| Residential MBS
Assets:
Debt securities available-for-sale	0	0
Recurring \| Level 1 \| Commercial MBS
Assets:
Debt securities available-for-sale	0	0
Recurring \| Level 1 \| Corporate bonds
Assets:
Debt securities available-for-sale	0	0
Recurring \| Level 1 \| Asset-backed securities
Assets:
Debt securities available-for-sale	0	0
Recurring \| Level 2
Assets:
Equity securities with readily determinable fair values	1,302	913
Mortgage loans held for sale	44,109	105,433
Deferred compensation plan assets	0	0
Servicing rights for SBA/USDA loans	0	0
Residential mortgage servicing rights	0	0
Derivative financial instruments	35,722	75,887
Total assets	4,358,042	3,277,132
Liabilities:
Deferred compensation plan liability	0	0
Derivative financial instruments	20,097	26,595
Total liabilities	20,097	26,595
Recurring \| Level 2 \| U.S. Treasuries
Assets:
Debt securities available-for-sale	0	0
Recurring \| Level 2 \| U.S. Government agencies & GSEs
Assets:
Debt securities available-for-sale	187,032	152,972
Recurring \| Level 2 \| State and political subdivisions
Assets:
Debt securities available-for-sale	275,844	274,472
Recurring \| Level 2 \| Residential MBS
Assets:
Debt securities available-for-sale	2,145,134	1,485,585
Recurring \| Level 2 \| Commercial MBS
Assets:
Debt securities available-for-sale	873,851	549,131
Recurring \| Level 2 \| Corporate bonds
Assets:
Debt securities available-for-sale	190,771	70,017
Recurring \| Level 2 \| Asset-backed securities
Assets:
Debt securities available-for-sale	604,277	562,722
Recurring \| Level 3
Assets:
Equity securities with readily determinable fair values	0	0
Mortgage loans held for sale	0	0
Deferred compensation plan assets	0	0
Servicing rights for SBA/USDA loans	6,513	6,462
Residential mortgage servicing rights	25,161	16,216
Derivative financial instruments	6,758	10,779
Total assets	40,827	35,207
Liabilities:
Deferred compensation plan liability	0	0
Derivative financial instruments	5,048	2,408
Total liabilities	5,048	2,408
Recurring \| Level 3 \| U.S. Treasuries
Assets:
Debt securities available-for-sale	0	0
Recurring \| Level 3 \| U.S. Government agencies & GSEs
Assets:
Debt securities available-for-sale	0	0
Recurring \| Level 3 \| State and political subdivisions
Assets:
Debt securities available-for-sale	0	0
Recurring \| Level 3 \| Residential MBS
Assets:
Debt securities available-for-sale	0	0
Recurring \| Level 3 \| Commercial MBS
Assets:
Debt securities available-for-sale	0	0
Recurring \| Level 3 \| Corporate bonds
Assets:
Debt securities available-for-sale	2,395	1,750
Recurring \| Level 3 \| Asset-backed securities
Assets:
Debt securities available-for-sale	$ 0	$ 0

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Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI), classified as current.

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Fair value of financial and nonfinancial obligations.

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Fair value portion of mortgage loans held-for-sale.

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Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

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