Disclosures About Fair Value of Financial Instruments - Balance Sheet Grouping (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Available-for-sale securities	$ 262,816	$ 276,021
Held-to-maturity securities	40,095	41,996
Loans held for sale		384
Loans held for investment	3,168,183	3,130,669	$ 1,810,842
Real estate acquired by foreclosure	9,230	12,122
Level 1 [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Cash and short term investments	171,421	124,906
Available-for-sale securities	75,047	74,974
Other securities	24,078	20,320
Loans held for sale		384
Total	270,546	220,584
Level 2 [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Available-for-sale securities	187,769	201,047
Held-to-maturity securities	40,095	41,996
Total	227,864	243,043
Financial Liabilities:
Deposits	3,066,745	3,100,748
Securities sold under agreements to repurchase	3,544	3,073
Other borrowed funds	328,077	221,104
Subordinated debentures	13,292	13,187
Total	3,411,658	3,338,112
Level 3 [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Loans held for investment	3,195,387	3,147,615
Real estate acquired by foreclosure	9,230	12,122
Total	3,204,617	3,159,737
Carrying Value [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Cash and short term investments	171,421	124,906
Available-for-sale securities	262,816	276,021
Held-to-maturity securities	40,022	42,130
Other securities	24,078	20,320
Loans held for sale		384
Loans held for investment	3,168,183	3,130,669
Real estate acquired by foreclosure	9,230	12,122
Total	3,675,750	3,606,552
Financial Liabilities:
Deposits	3,057,019	3,100,748
Securities sold under agreements to repurchase	3,544	3,073
Other borrowed funds	328,968	223,265
Subordinated debentures	13,292	13,187
Total	3,402,823	3,340,273
Fair Value [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Cash and short term investments	171,421	124,906
Available-for-sale securities	262,816	276,021
Held-to-maturity securities	40,095	41,996
Other securities	24,078	20,320
Loans held for sale		384
Loans held for investment	3,195,387	3,147,615
Real estate acquired by foreclosure	9,230	12,122
Total	3,703,027	3,623,364
Financial Liabilities:
Deposits	3,066,745	3,100,748
Securities sold under agreements to repurchase	3,544	3,073
Other borrowed funds	328,077	221,104
Subordinated debentures	13,292	13,187
Total	$ 3,411,658	$ 3,338,112

Fair value portion of subordinated debentures.

No definition available.

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- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
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- Definition

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

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Cash
-URI http://asc.fasb.org/extlink&oid=6506951

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-Name Accounting Standards Codification
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- Definition

Fair value portion of investments accounted under the cost method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 325
-SubTopic 20
-Section 25
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Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

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.

+ References

No definition available.

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No definition available.

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Fair value of financial obligations, including, but not limited to, debt instruments, derivative liabilities, federal funds purchased and sold under agreements to repurchase, securities loaned or sold under agreements to repurchase, financial instruments sold not yet purchased, guarantees, line of credit, loans and notes payable, servicing liability, and trading liabilities.

+ References

No definition available.

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Fair value of investments in debt securities classified as held-to-maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
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Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

+ References

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The face amount of loans that will be sold to other entities.

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Carrying amount as of the balance sheet date of land and buildings obtained through foreclosure proceedings or defeasance in full or partial satisfaction of a debt arrangement.

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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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