XML 28 R91.htm IDEA: XBRL DOCUMENT
v3.20.1

Allowance for Loan and Lease Losses and Reserve for Unfunded Commitments - Additional Information (Details) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Loans And Leases Receivable Disclosure [Line Items] |  |  |
Increase (decrease) in allowance for loan and lease losses | $ 6,700,000 | $ 8,500,000 | $ 5,800,000
Commitments outstanding on troubled debt restructurings | 500,000 | 500,000 | 0
Recorded investment in troubled debt restructurings that subsequently defaulted within twelve months | 348,000 | 340,000 | 144,000
Reserve for unfunded commitments | 1,200,000 | 1,200,000 |
Provisions for unfunded commitments | 80,000 | 317,000 | 162,000
Charge-offs or recoveries related to reserve for unfunded commitments | 0 | 0 | 0
Acquired Impaired Loans |  |  |
Loans And Leases Receivable Disclosure [Line Items] |  |  |
Increase (decrease) in allowance for loan and lease losses | 41,000 | (1,100,000) | 2,300,000
Individually Evaluated For Impairment |  |  |
Loans And Leases Receivable Disclosure [Line Items] |  |  |
Increase (decrease) in allowance for loan and lease losses | 4,000,000 | 2,700,000 | 2,900,000
Collectively Evaluated For Impairment |  |  |
Loans And Leases Receivable Disclosure [Line Items] |  |  |
Increase (decrease) in allowance for loan and lease losses | $ 2,700,000 | $ 7,000,000 | $ 572,000

X
- Definition Charge-offs or recoveries related to the reserve for unfunded commitments. + References No definition available. + Details
Name: | by_ChargeOffsOrRecoveriesRelatedToReserveForUnfundedCommitments
Namespace Prefix: | by_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Provision for unfunded commitments. + References No definition available. + Details
Name: | by_ProvisionForUnfundedCommitments
Namespace Prefix: | by_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Reserve for unfunded commitments. + References No definition available. + Details
Name: | by_ReserveForUnfundedCommitments
Namespace Prefix: | by_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Troubled debt restructurings, commitments outstanding. + References No definition available. + Details
Name: | by_TroubledDebtRestructuringsCommitmentsOutstanding
Namespace Prefix: | by_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of increase (decrease) of allowance reserve for credit loss. + 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 210.9-03.7(d)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
Name: | us-gaap_AllowanceForLoanAndLeaseLossesPeriodIncreaseDecrease
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of financing receivable modified as troubled debt restructuring within previous 12 months, with subsequent payment default. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 34 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953682-111524 + Details
Name: | us-gaap_FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_LoansAndLeasesReceivableDisclosureLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=by_AcquiredImpairedLoansMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=by_IndividuallyEvaluatedForImpairmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=by_CollectivelyEvaluatedForImpairmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |