The amount of debt discount related to acquired receivables.

No definition available.

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- Definition

The amount of debt discount related to certain loans acquired in transfer with evidence of deterioration of credit quality since origination.

+ References

No definition available.

+ Details

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- Definition

This element represents the aggregate threshold which non-homogeneous loan relationships are analyzed on an annual basis for credit risk ratings.

+ References

No definition available.

+ Details

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- Definition

Fair value of acquired receivable from business combination, excluding certain loans and debt securities acquired in transfer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=84161108&loc=d3e4845-128472

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- Definition

For receivables acquired in a business combination, excluding certain loans and debt securities acquired in a transfer (as defined), this element represents the gross contractual amounts receivable, by major class of receivable, such as loans, direct finance leases (as defined), and any other class of receivables.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=84161108&loc=d3e4845-128472

+ Details

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- Definition

The recorded balance, net of any applicable reductions (for example, unamortized accretable yield and allowance for loan losses). This relates to loans not accounted for debt securities with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=82894903&loc=d3e15032-111544

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 15
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82894507&loc=d3e13503-111538

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- Definition

The undiscounted sum of all amounts, including amounts deemed principal, interest, fees, penalties, and other under the loan, owed to the investor at the reporting date, whether or not currently due and whether or not any such amounts have been written or charged off by the investor. This relates to loans not accounted for as debt securities, with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 15
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82894507&loc=d3e13503-111538

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=82894903&loc=d3e15032-111544

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Period Type:	instant

- Definition

Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953676-111524

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Period Type:	duration

- Definition

The amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=82895541&loc=d3e18845-111554

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- Definition

Number of financing receivables that have been modified by troubled debt restructurings within the previous 12 months and for which there was a payment default.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953682-111524

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- Definition

Amount of investment related to financing receivables modified by troubled debt restructurings within the previous 12 months, for which there was a payment default.

+ References

+ Details

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Period Type:	duration

- Definition

Recorded investment in financing receivables that are 90 days or more past due and still accruing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5111-111524

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Balance Type:	debit
Period Type:	instant

- Definition

Reflects the unfunded portion of contractual agreements to lend funds to borrowers for loans whose terms have been modified by troubled debt restructuring.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82895541&loc=d3e18794-111554

+ Details

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Period Type:	instant

- Definition

Carrying amount as of the balance sheet date of loans that have been pledged as collateral for borrowings. If the secured party has the right by contract or custom to sell or re-pledge the collateral, then the debtor reclassifies that asset and report that asset in its statement of financial position separately from other assets not so encumbered.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66007379&loc=d3e113888-111728

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5086-111524

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

Recorded investment of consumer mortgage loan receivables secured by residential real estate properties for which formal foreclosure proceedings are in process.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 35
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL49126937-111524

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Balance Type:	debit
Period Type:	instant

- Definition

Amount representing an agreement for an unconditional promise by the maker to pay the entity (holder) a definite sum of money at a future date. Such amount may include accrued interest receivable in accordance with the terms of the note. The note also may contain provisions and related items including a discount or premium, payable on demand, secured, or unsecured, interest bearing or noninterest bearing, among a myriad of other features and characteristics. Excludes amounts related to receivables held-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.10(3))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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Note 5 - Loans Receivable (Details Textual)	12 Months Ended
Note 5 - Loans Receivable (Details Textual)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015	Oct. 01, 2015 USD ($)	Jun. 13, 2014 USD ($)
Financing Receivable, Gross	$ 1,672,859,000	$ 1,555,904,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net	6,220,000	12,384,000			$ 21,105,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Outstanding Balance	8,529,000	15,468,000			26,942,000
Financing Receivable, Modifications, Recorded Investment	5,580,000	$ 5,999,000
Minimum Loan Amount for Loans Analyzed by Credit Risk	$ 1,000,000
Financing Receivable, Modifications, Number of Contracts	1	4	0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	2	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 4,500,000
Loans and Leases Receivable, Impaired, Commitment to Lend	0	$ 0
Doubtful [Member]
Financing Receivable, Gross	0	0
Unlikely to be Collected Financing Receivable [Member]
Financing Receivable, Gross	0	0
Nonaccrual [Member]
Financing Receivable, Modifications, Recorded Investment	4,698,000	1,195,000
Mortgage Loans in Process of Foreclosure, Amount	2,600,000	1,000,000
Purchased Credit Impaired [Member]
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	500,000	800,000
One-to-Four-Family Residential [Member] \| Real Estate Portfolio Segment [Member]
Financing Receivable, Gross	391,225,000	389,107,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net	2,210,000	2,714,000			4,728,000
Financing Receivable, Modifications, Recorded Investment	279,000	$ 512,000
Mortgage Loans in Process of Foreclosure, Amount	1,000,000
Financing Receivable, Modifications, Number of Contracts		1
One-to-Four-Family Residential [Member] \| Nonaccrual [Member] \| Real Estate Portfolio Segment [Member]
Financing Receivable, Modifications, Recorded Investment	90,000	$ 315,000
Mortgage Loans in Process of Foreclosure, Amount	1,000,000	500,000
First National Security Company [Member]
Business Combination, Acquired Receivable, Fair Value					583,600,000
Business Combination, Acquired Receivables, Gross Contractual Amount					595,100,000
Business Combination Acquired Receivables Discount					11,500,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net					21,100,000
Certain Loans Acquired in Transfer not Accounted for as Debt Securities Discount					$ 5,800,000
Acquisition of MNB [Member]
Business Combination, Acquired Receivable, Fair Value				$ 364,500,000
Business Combination, Acquired Receivables, Gross Contractual Amount				375,000,000
Business Combination Acquired Receivables Discount				$ 10,500,000
Federal Home Loan Bank of Dallas [Member]
Loans Pledged as Collateral	21,700,000	26,400,000
Serviced for Others [Member]
Financing Receivable, Gross	$ 3,800,000	$ 14,700,000