Fair Value Measurements Not Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets:
Cash and cash equivalents		$ 120,541
Investment securities held-to-maturity	$ 68,595	73,781
Loans held for sale		4,737
Loans, net		6,388,297
Other financial assets		93,449
FINANCIAL LIABILITIES:
Deposits		6,509,197
Securities sold under agreements to repurchase		32,169
Securities sold under agreements to repurchase		30,000
Federal Home Loan Bank borrowings		692,402
Junior subordinated debentures		96,363
Other financial liabilities		2,224
Fair Value, Inputs, Level 1
Assets:
Cash and cash equivalents		120,541
Investment securities held-to-maturity		0
Loans held for sale		0
Loans, net		0
Other financial assets		0
FINANCIAL LIABILITIES:
Deposits		0
Securities sold under agreements to repurchase		0
Securities sold under agreements to repurchase		0
Federal Home Loan Bank borrowings		0
Junior subordinated debentures		0
Other financial liabilities		0
Fair Value, Inputs, Level 2
Assets:
Cash and cash equivalents		0
Investment securities held-to-maturity		73,781
Loans held for sale		4,737
Loans, net		0
Other financial assets		93,449
FINANCIAL LIABILITIES:
Deposits		6,509,197
Securities sold under agreements to repurchase		32,169
Securities sold under agreements to repurchase		30,000
Federal Home Loan Bank borrowings		692,402
Junior subordinated debentures		0
Other financial liabilities		2,224
Fair Value, Inputs, Level 3
Assets:
Cash and cash equivalents		0
Investment securities held-to-maturity		0
Loans held for sale		0
Loans, net		6,388,297
Other financial assets		0
FINANCIAL LIABILITIES:
Deposits		0
Securities sold under agreements to repurchase		0
Securities sold under agreements to repurchase		0
Federal Home Loan Bank borrowings		0
Junior subordinated debentures		96,363
Other financial liabilities		0
Reported Value Measurement
Assets:
Cash and cash equivalents	127,259	120,541
Investment securities held-to-maturity	70,438	74,576
Loans held for sale	2,812	4,697
Loans, net	6,817,846	6,430,286
Other financial assets	78,730	93,449
FINANCIAL LIABILITIES:
Deposits	6,781,170	6,510,246
Securities sold under agreements to repurchase	36,928	32,169
Securities sold under agreements to repurchase	250,000	30,000
Federal Home Loan Bank borrowings	420,144	693,681
Junior subordinated debentures	106,363	106,363
Other financial liabilities	2,001	$ 2,224
Estimate of Fair Value Measurement
Assets:
Cash and cash equivalents	127,259
Investment securities held-to-maturity	68,595
Loans held for sale	2,837
Loans, net	6,734,216
Other financial assets	78,730
FINANCIAL LIABILITIES:
Deposits	6,777,928
Securities sold under agreements to repurchase	36,928
Securities sold under agreements to repurchase	250,000
Federal Home Loan Bank borrowings	417,092
Junior subordinated debentures	96,363
Other financial liabilities	2,001
Estimate of Fair Value Measurement \| Fair Value, Inputs, Level 1
Assets:
Cash and cash equivalents	127,259
Investment securities held-to-maturity	0
Loans held for sale	0
Loans, net	0
Other financial assets	0
FINANCIAL LIABILITIES:
Deposits	0
Securities sold under agreements to repurchase	0
Securities sold under agreements to repurchase	0
Federal Home Loan Bank borrowings	0
Junior subordinated debentures	0
Other financial liabilities	0
Estimate of Fair Value Measurement \| Fair Value, Inputs, Level 2
Assets:
Cash and cash equivalents	0
Investment securities held-to-maturity	68,595
Loans held for sale	2,837
Loans, net	0
Other financial assets	78,730
FINANCIAL LIABILITIES:
Deposits	6,777,928
Securities sold under agreements to repurchase	36,928
Securities sold under agreements to repurchase	250,000
Federal Home Loan Bank borrowings	417,092
Junior subordinated debentures	0
Other financial liabilities	2,001
Estimate of Fair Value Measurement \| Fair Value, Inputs, Level 3
Assets:
Cash and cash equivalents	0
Investment securities held-to-maturity	0
Loans held for sale	0
Loans, net	6,734,216
Other financial assets	0
FINANCIAL LIABILITIES:
Deposits	0
Securities sold under agreements to repurchase	0
Securities sold under agreements to repurchase	0
Federal Home Loan Bank borrowings	0
Junior subordinated debentures	96,363
Other financial liabilities	$ 0

No definition available.

Name:	us-gaap_AssetsFairValueDisclosureAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- 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

No definition available.

+ Details

Name:	us-gaap_CashAndCashEquivalentsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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.

+ Details

Name:	us-gaap_DepositsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

+ Details

Name:	us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisSubordinatedDebtObligations
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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

+ Details

Name:	us-gaap_FederalFundsPurchasedFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value portion of borrowing from Federal Home Loan Bank (FHLBank).

+ References

+ Details

Name:	us-gaap_FederalHomeLoanBankBorrowingsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_FinancialLiabilitiesFairValueDisclosureAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value of investment in debt security measured at amortized cost (held-to-maturity).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563

+ Details

Name:	us-gaap_HeldToMaturitySecuritiesFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

+ References

No definition available.

+ Details

Name:	us-gaap_LoansHeldForSaleFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-URI http://asc.fasb.org/subtopic&trid=2196772

+ Details

Name:	us-gaap_LoansReceivableFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value portion of other assets.

+ References

No definition available.

+ Details

Name:	us-gaap_OtherAssetsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value portion of other liabilities.

+ References

No definition available.

+ Details

Name:	us-gaap_OtherLiabilitiesFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value portion of securities that an entity sells and agrees to repurchase at a specified date for a specified price.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13433-108611

+ Details

Name:	us-gaap_SecuritiesLoanedOrSoldUnderAgreementsToRepurchaseFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByMeasurementBasisAxis=us-gaap_CarryingReportedAmountFairValueDisclosureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByMeasurementBasisAxis=us-gaap_EstimateOfFairValueFairValueDisclosureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: