Fair Value - Carrying Amount and Fair Value of Other Significant Financial Instruments Not Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Financial Assets
Debt securities held to maturity	$ 295,485	$ 357,949
Loans, net	4,795,619	4,792,791
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	291,340	349,895
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	61,039	61,224
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3)
Financial Assets
Debt securities held to maturity	0	0
Time deposits with other banks	8,105	8,132
Loans, net	4,760,789	4,835,248
Financial Liabilities
Deposit liabilities	5,603,019	5,172,098
Federal Home Loan Bank (FHLB) borrowings	3,000	380,027
Subordinated debt	0	0
Carrying Value \| Fair Value, Measurements, Recurring
Financial Assets
Debt securities held to maturity	295,485	357,949
Time deposits with other banks	8,174	8,243
Loans, net	4,787,307	4,784,201
Financial Liabilities
Deposit liabilities	5,605,578	5,177,240
Federal Home Loan Bank (FHLB) borrowings	3,000	380,000
Subordinated debt	$ 70,874	$ 70,804

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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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-Section 50
-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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-Topic 320
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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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