Fair Value Disclosures (Details 3) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	$ 206,832	$ 214,257
Loans held for sale	454,600	2,571,300
Subordinated notes	282,309	282,129
Level 1 \| Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	20,862	18,484
Level 1 \| Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	9,716,584	4,425,583
Investment securities	20,862	18,484
Level 2 \| Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	11,737	12,396
Loans held for sale	448,422	2,570,091
Derivative assets		48,684
Federal funds purchased	189,030	132,270
Customer repurchase agreements	6,760	9,496
Other borrowings	2,700,000	2,400,000
Subordinated notes	282,309	282,129
Trust preferred subordinated debentures	113,406	113,406
Derivative liabilities		51,310
Level 2 \| Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	11,737	12,396
Loans held for sale	448,422	2,570,091
Derivative assets	143,050	48,684
Federal funds purchased	189,030	132,270
Customer repurchase agreements	6,760	9,496
Other borrowings	2,700,000	2,400,000
Subordinated notes	291,821	292,302
Trust preferred subordinated debentures	113,406	113,406
Derivative liabilities	126,542	51,310
Level 3 \| Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	202,370	208,991
Loans held for sale	6,159	7,043
Loans held for investment, net	25,260,107	24,451,215
Deposits	30,187,695	26,478,593
Level 3 \| Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	202,370	208,991
Loans held for sale	6,159	7,043
Loans held for investment, net	25,249,741	24,478,586
Deposits	$ 30,192,842	$ 26,486,090

Amount 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 portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

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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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Fair value of subordinated debt obligations including, but not limited to, subordinated loan, subordinated bond, subordinated debenture or junior debt.

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Fair value portion of short term borrowing where a bank borrows, at the federal funds rate, from another bank.

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Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

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Fair value portion of securities that an entity sells and agrees to repurchase at a specified date for a specified price.

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