Fair Value - Fair Value Measurements of Other Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Assets
Cash and due from banks	$ 270,020	$ 196,364
Interest-bearing deposits in other banks	1,654,917	920,880
Securities held-to-maturity	10,853	12,071
FHLB and FRB stock	106,090	117,420
Loans	14,582,491	14,512,215
Investment in BOLI	300,387	301,101
Liabilities
Deposits	17,198,402	16,012,464
Borrowed funds	1,274,572	1,546,414
Senior and subordinated debt	235,383	234,768
Carrying Amount \| Level 1
Assets
Cash and due from banks	270,020	196,364
Carrying Amount \| Level 2
Assets
Interest-bearing deposits in other banks	1,654,917	920,880
Securities held-to-maturity	10,853	12,071
FHLB and FRB stock	106,090	117,420
Liabilities
Deposits	17,198,402	16,012,464
Borrowed funds	1,274,572	1,546,414
Senior and subordinated debt	235,383	234,768
Accrued interest payable	2,915	4,826
Carrying Amount \| Level 3
Assets
Loans	14,582,491	14,512,215
Investment in BOLI	300,387	301,101
Accrued interest receivable	62,018	68,390
Fair Value \| Level 1
Assets
Cash and due from banks	270,020	196,364
Fair Value \| Level 2
Assets
Interest-bearing deposits in other banks	1,654,917	920,880
Securities held-to-maturity	10,461	11,686
FHLB and FRB stock	106,090	117,420
Liabilities
Deposits	17,199,593	16,007,133
Borrowed funds	1,274,572	1,546,414
Senior and subordinated debt	283,439	281,843
Accrued interest payable	2,915	4,826
Fair Value \| Level 3
Assets
Loans	14,425,048	14,614,029
Investment in BOLI	300,387	301,101
Accrued interest receivable	$ 62,018	$ 68,390

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The carrying amount of a life insurance policy on an officer, executive or employee for which the reporting entity (a bank) is entitled to proceeds from the policy upon death of the insured or surrender of the insurance policy.

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For banks and other depository institutions: Includes cash on hand (currency and coin), cash items in process of collection, noninterest bearing deposits due from other financial institutions (including corporate credit unions), and noninterest bearing balances with the Federal Reserve Banks, Federal Home Loan Banks and central banks.

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Amount excluding accrued interest, before allowance for credit loss, of investment in debt security measured at amortized cost (held-to-maturity).

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The aggregate of all deposit liabilities held by the entity, including foreign and domestic, interest and noninterest bearing; may include demand deposits, saving deposits, Negotiable Order of Withdrawal (NOW) and time deposits among others.

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Amount of Federal Home Loan Bank (FHLB) and Federal Reserve Bank stock.

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Amount excluding accrued interest, after allowance for credit loss, of financing receivable.

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For banks and other depository institutions (including Federal Reserve Banks, if applicable): Interest-bearing deposits in other financial institutions for relatively short periods of time including, for example, certificates of deposits, which are presented separately from cash on the balance sheet.

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Carrying amount as of the balance sheet date of interest earned but not received. Also called accrued interest or accrued interest receivable.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

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