XML 65 R79.htm IDEA: XBRL DOCUMENT v3.20.1

Securities - Summary of Gross Unrealized Losses and Fair Values, Aggregated by Investment Category and Length of Individual Securities Continuous Unrealized Loss Position Held-to-maturity (Details) $ in Thousands	Dec. 31, 2018 USD ($) Security
Schedule Of Held To Maturity Securities [Line Items]
Held-to-maturity Securities, Continuous Unrealized Loss Position, Number of Securities | Security	46
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 36,251
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(711)
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	42,862
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	(949)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Total Fair Value	79,113
Held-to-maturity Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (1,660)
Obligations of States, Municipalities, and Political Subdivisions
Schedule Of Held To Maturity Securities [Line Items]
Held-to-maturity Securities, Continuous Unrealized Loss Position, Number of Securities | Security	23
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 8,127
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(58)
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	8,792
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	(152)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Total Fair Value	16,919
Held-to-maturity Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (210)
Agency, Residential Mortgage-Backed Securities
Schedule Of Held To Maturity Securities [Line Items]
Held-to-maturity Securities, Continuous Unrealized Loss Position, Number of Securities | Security	16
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 6,625
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(150)
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	21,139
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	(381)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Total Fair Value	27,764
Held-to-maturity Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (531)
Non-Agency, Residential Mortgage-Backed Securities
Schedule Of Held To Maturity Securities [Line Items]
Held-to-maturity Securities, Continuous Unrealized Loss Position, Number of Securities | Security	7
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 21,499
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(503)
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	12,931
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	(416)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Total Fair Value	34,430
Held-to-maturity Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (919)

X

- Definition

Held to maturity securities in unrealized loss positions qualitative disclosure number of securities.

+ References

No definition available.

+ Details

Name:	by_HeldToMaturitySecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfSecurities
Namespace Prefix:	by_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in continuous loss position for 12 months or longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27337-111563

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27290-111563

+ Details

Name:	us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in unrealized loss position.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27290-111563

+ Details

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

X

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27290-111563

+ Details

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

X

- Definition

Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in continuous loss position for less than 12 months.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27290-111563

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27337-111563

+ Details

Name:	us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Fair value of investment in debt security measured at amortized cost (held-to-maturity), in continuous unrealized loss position for less than 12 months.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27337-111563

+ Details

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

X

- Definition

Fair value of investment in debt security measured at amortized cost (held-to-maturity), in continuous unrealized loss position for 12 months or longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27337-111563

+ Details

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

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

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=by_AgencyResidentialMortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=by_NonAgencyResidentialMortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: