Disclosures about Fair Value of Financial Instruments - Estimated Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents, carrying value	$ 264,593	$ 371,023	$ 233,068	$ 186,016
Cash and cash equivalents, fair value	264,593	371,023
Investment securities available for sale, carrying value	560,253	416,685
Investment securities available for sale, fair value	560,253	416,685
Loans held for sale, carrying value	1,797,064	1,435,459
Loans held for sale, fair value	1,797,458	1,436,460
Loans receivable, net of allowance for loan losses, carrying value	5,417,832	4,281,241
Loans receivable, net of allowance for loan losses, fair value	5,353,903	4,285,537
FHLB, Federal Reserve Bank and other restricted stock, carrying value	90,841	82,002
FHLB, Federal Reserve Bank and other restricted stock, fair value	90,841	82,002
Derivative assets, carrying value	9,295	7,552
Derivative assets, fair value	9,295	7,552
Deposits, carrying value	5,909,501	4,532,538
Deposits, fair value	5,911,754	4,540,507
Federal funds purchased, carrying value	70,000	0
Federal funds purchased, fair value	70,000
FHLB advances, carrying value	1,625,300	1,618,000
FHLB advances, fair value	1,625,468	1,619,858
Other borrowings, carrying value	88,250	88,250
Other borrowings, fair value	93,804	92,069
Subordinated debt, carrying value	110,000	110,000
Subordinated debt, fair value	110,825	111,925
Derivative liabilities, carrying value	13,932	9,716
Derivative liabilities, fair value	13,932	9,716
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents, fair value	264,593	371,023
Investment securities available for sale, carrying value	19,212	24,270
Investment securities available for sale, fair value	19,212	24,270
Loans held for sale, fair value	0	0
Loans receivable, net of allowance for loan losses, fair value	0	0
FHLB, Federal Reserve Bank and other restricted stock, fair value	0	0
Derivative assets, carrying value	0	0
Derivative assets, fair value	0	0
Deposits, fair value	3,561,905	2,820,875
Federal funds purchased, fair value	70,000
FHLB advances, fair value	1,365,300	1,298,000
Other borrowings, fair value	68,867	66,944
Subordinated debt, fair value	0	0
Derivative liabilities, carrying value	0	0
Derivative liabilities, fair value	0	0
Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents, fair value	0	0
Investment securities available for sale, carrying value	541,041	392,415
Investment securities available for sale, fair value	541,041	392,415
Loans held for sale, fair value	1,757,807	1,335,668
Loans receivable, net of allowance for loan losses, fair value	0	0
FHLB, Federal Reserve Bank and other restricted stock, fair value	90,841	82,002
Derivative assets, carrying value	9,250	7,509
Derivative assets, fair value	9,250	7,509
Deposits, fair value	2,349,849	1,719,632
Federal funds purchased, fair value	0
FHLB advances, fair value	260,168	321,858
Other borrowings, fair value	24,937	25,125
Subordinated debt, fair value	110,825	111,925
Derivative liabilities, carrying value	13,932	9,716
Derivative liabilities, fair value	13,932	9,716
Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents, fair value	0	0
Investment securities available for sale, carrying value	0	0
Investment securities available for sale, fair value	0	0
Loans held for sale, fair value	39,651	100,792
Loans receivable, net of allowance for loan losses, fair value	5,353,903	4,285,537
FHLB, Federal Reserve Bank and other restricted stock, fair value	0	0
Derivative assets, carrying value	45	43
Derivative assets, fair value	45	43
Deposits, fair value	0	0
Federal funds purchased, fair value	0
FHLB advances, fair value	0	0
Other borrowings, fair value	0	0
Subordinated debt, fair value	0	0
Derivative liabilities, carrying value	0	0
Derivative liabilities, fair value	$ 0	$ 0

Borrowings Fair Value Disclosure

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- Definition

Federal Home Loan Bank Stock And Federal Reserve Bank Stock Fair Value

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Fair value of Federal Home Loan Bank (FHLBank) advances carried under the fair value option.

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Amount 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. Excludes cash and cash equivalents within disposal group and discontinued operation.

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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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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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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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No definition available.

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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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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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

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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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Amount of advances from the Federal Home Loan Bank (FHLB).

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

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No definition available.

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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums over and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes loans and leases covered under loss sharing agreements.

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No definition available.

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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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No definition available.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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Amount, after allowance for bad debt, of loan receivables held-for-sale that are not part of a disposal group. Excludes loans and leases covered under loss sharing agreements and loans classified as debt securities.

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The carrying amount as of the balance sheet date for the aggregate of other miscellaneous borrowings owed by the reporting entity.

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Fair value of all derivative liabilities not designated as a hedging instrument.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of subordinated debt (with initial maturities beyond one year or beyond the operating cycle if longer). Subordinated debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets.

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