Fair Value Disclosures (Details 3) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	$ 214,257	$ 103,046
Loans held for sale	2,571,300	1,969,200
Subordinated notes	282,129	281,767
Level 1 \| Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	18,484	10,262
Level 1 \| Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	4,425,583	3,080,065
Investment securities	18,484	10,262
Level 2 \| Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	12,396	14,150
Loans held for sale	2,570,091	1,953,059
Derivative assets	48,684	21,806
Federal funds purchased	132,270	629,169
Customer repurchase agreements	9,496	12,005
Other borrowings	2,400,000	3,900,000
Subordinated notes	282,129	281,767
Derivative liabilities	51,310	41,375
Level 2 \| Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	12,396	14,150
Loans held for sale	2,570,091	1,953,059
Derivative assets	48,684	21,806
Federal funds purchased	132,270	629,169
Customer repurchase agreements	9,496	12,005
Other borrowings	2,400,000	3,900,000
Subordinated notes	292,302	283,349
Derivative liabilities	51,310	41,375
Level 3 \| Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	208,991	95,804
Loans held for sale	7,043	16,415
Loans held for investment, net	24,451,215	22,376,552
Deposits	26,478,593	20,606,113
Trust preferred subordinated debentures	113,406	113,406
Level 3 \| Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	208,991	95,804
Loans held for sale	7,043	16,415
Loans held for investment, net	24,478,586	22,347,876
Deposits	29,357,121	20,608,494
Trust preferred subordinated debentures	$ 113,406	$ 113,406

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 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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