Fair Value - Carrying Amount and Fair Value of Other Significant Financial Instruments Not Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Financial Assets
Debt securities held to maturity	$ 367,387	$ 416,863
Loans, net	4,025,458	3,790,255
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial Assets
Debt securities held to maturity	0	0
Time deposits with other banks	0	0
Loans, net	0	0
Financial Liabilities
Deposit liabilities	0	0
Federal Home Loan Bank (FHLB) borrowings	0	0
Subordinated debt	0	0
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2)
Financial Assets
Debt securities held to maturity	353,919	414,470
Time deposits with other banks	0	0
Loans, net	0	0
Financial Liabilities
Deposit liabilities	0	0
Federal Home Loan Bank (FHLB) borrowings	0	0
Subordinated debt	61,716	61,530
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3)
Financial Assets
Debt securities held to maturity	0	0
Time deposits with other banks	9,715	12,493
Loans, net	3,982,029	3,760,754
Financial Liabilities
Deposit liabilities	4,638,270	4,588,515
Federal Home Loan Bank (FHLB) borrowings	261,036	211,000
Subordinated debt	0	0
Carrying Value \| Fair Value, Measurements, Recurring
Financial Assets
Debt securities held to maturity	367,387	416,863
Time deposits with other banks	9,813	12,553
Loans, net	4,018,190	3,786,063
Financial Liabilities
Deposit liabilities	4,643,510	4,592,720
Federal Home Loan Bank (FHLB) borrowings	261,000	211,000
Subordinated debt	$ 70,734	$ 70,521

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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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Amount of interest-bearing funds deposited into another Federal Home Loan Banks (FHLBanks).

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- Definition

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

+ 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 (b)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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-Name Accounting Standards Codification
-Topic 820
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-Paragraph 2
-Subparagraph (a)
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Fair value portion of borrowing from Federal Home Loan Bank (FHLBank).

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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 210.9-03.13(3)(a))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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Amount after other than temporary impairment (OTTI) accretion, 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
-Subparagraph (a)
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-Publisher FASB
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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

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