XML 61 R50.htm IDEA: XBRL DOCUMENT
v3.21.1

Investment Securities - Visa Class B Restricted Shares (Details) - Visa $ in Thousands | 3 Months Ended |
--- | --- | ---
Mar. 31, 2021 USD ($) shares | Dec. 31, 2020 USD ($)
Common Class A |  |
Securities |  |
Investment shares owned, if converted | 11,236 |
Common Class B |  |
Securities |  |
Conversion ratio | 1.6228 |
Investment shares owned | 6,924 |
Cost basis | $ | $ 0 | $ 0

X
- Definition Cost basis carrying value of equity security class shares. + References No definition available. + Details
Name: | alrs_CarryingValueOfEquitySecurityClassShares
Namespace Prefix: | alrs_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Conversion ratio from Class B shares to Class A. + References No definition available. + Details
Name: | alrs_ClassShareConversionRatio
Namespace Prefix: | alrs_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | duration

X
- Definition Balance of shares at end of period, if converted. + References No definition available. + Details
Name: | alrs_InvestmentOwnedSharesIfConverted
Namespace Prefix: | alrs_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Balance held at close of period in number of shares. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 210 -Section 50 -Paragraph 6 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=99383244&loc=d3e12121-115841 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-12B(Column B)) -URI http://asc.fasb.org/extlink&oid=120401592&loc=d3e611197-123010 + Details
Name: | us-gaap_InvestmentOwnedBalanceShares
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
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_MarketableSecuritiesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=alrs_VisaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=us-gaap_CommonClassAMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=us-gaap_CommonClassBMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |