Fair Value of Financial Instruments (Details) - USD ($)	Jun. 30, 2019	Jun. 30, 2018
Available-for-Sale Securities
Mutual funds		$ 1,728,000
Held-to-maturity securities, maturities less than 1 year		1,328,000
Held-to-maturity securities, maturities from 91-360 days		495,000
Held-to-maturity securities, maturities over 360 days		50,000
Investments		3,601,000
Mutual funds, fair value		1,728,000
Held-to-maturity securities, maturities less than 1 year, fair value		1,328,000
Held-to-maturity securities, maturities from 91-360 days, fair value		495,000
Held-to-maturity securities, maturities over 360 days, fair value		50,000
Investments, fair value	$ 0	3,601,000
Level 1
Available-for-Sale Securities
Mutual funds, fair value		1,728,000
Held-to-maturity securities, maturities less than 1 year, fair value		0
Held-to-maturity securities, maturities from 91-360 days, fair value		0
Held-to-maturity securities, maturities over 360 days, fair value		0
Investments, fair value		1,728,000
Level 2
Available-for-Sale Securities
Mutual funds, fair value		0
Held-to-maturity securities, maturities less than 1 year, fair value		1,328,000
Held-to-maturity securities, maturities from 91-360 days, fair value		495,000
Held-to-maturity securities, maturities over 360 days, fair value		50,000
Investments, fair value		1,873,000
Level 3
Available-for-Sale Securities
Mutual funds, fair value		0
Held-to-maturity securities, maturities less than 1 year, fair value		0
Held-to-maturity securities, maturities from 91-360 days, fair value		0
Held-to-maturity securities, maturities over 360 days, fair value		0
Investments, fair value		$ 0

Held-To-Maturity Securities, Debt Maturities, 91 To 360 Days, Fair Value

No definition available.

Name:	astc_HeldToMaturitySecuritiesDebtMaturities91To360DaysFairValue
Namespace Prefix:	astc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Held-To-Maturity Securities, Debt Maturities, 91 To 360 Days, Net Carrying Amount

+ References

No definition available.

+ Details

Name:	astc_HeldToMaturitySecuritiesDebtMaturities91To360DaysNetCarryingAmount
Namespace Prefix:	astc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Held-To-Maturity Securities, Debt Maturities, Over 360 Days, Fair Value

+ References

No definition available.

+ Details

Name:	astc_HeldToMaturitySecuritiesDebtMaturitiesOver360DaysFairValue
Namespace Prefix:	astc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Held-To-Maturity Securities, Debt Maturities, Over 360 Days, Net Carrying Amount

+ References

No definition available.

+ Details

Name:	astc_HeldToMaturitySecuritiesDebtMaturitiesOver360DaysNetCarryingAmount
Namespace Prefix:	astc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents the carrying value of the mutual funds.

+ References

No definition available.

+ Details

Name:	astc_MutualFundsCarryingValue
Namespace Prefix:	astc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents amount of fair value for mutual funds.

+ References

No definition available.

+ Details

Name:	astc_MutualFundsFairValue
Namespace Prefix:	astc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

No definition available.

+ Details

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

- 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_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems
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), with single maturity date and allocated without single maturity date, maturing in next fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

+ 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 (f)(1)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 320
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=75019621&loc=d3e62586-112803

+ Details

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

- Definition

Amount of investment in debt security measured at amortized cost (held-to-maturity), with single maturity date and allocated without single maturity date, maturing in next fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 320
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=75019621&loc=d3e62586-112803

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (f)(1)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563

+ Details

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

- Definition

Sum of the carrying amounts as of the balance sheet date of all investments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(h))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

Name:	us-gaap_Investments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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: