Investments - Carrying Value (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Jun. 30, 2016
Schedule of Held-to-maturity Securities [Line Items]
Available-for-sale securities, current	$ 12,848	$ 12,807
Held-to-maturity securities, maturities from 1-90 days	497	2,243
Held-to-maturity securities, maturities from 91-360 days	1,199	1,699
Held-to-maturity securities, maturities over 360 days	798	1,048
Held-to-maturity securities, maturities less than 1 year	654	353
Held-to-maturity securities, remaining maturities from 1-3 years	2,747	3,160
Held-to-maturity securities	5,895	8,503
Short-Term Investments
Schedule of Held-to-maturity Securities [Line Items]
Total available-for-sale and held-to-maturity securities	15,198	17,102
Long-Term Investments
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities	3,545	4,208
Mutual Funds - Corporate & Government Debt
Schedule of Held-to-maturity Securities [Line Items]
Available-for-sale securities, current	12,848	12,807
Mutual Funds - Corporate & Government Debt \| Short-Term Investments
Schedule of Held-to-maturity Securities [Line Items]
Available-for-sale securities, current	12,848	12,807
Time Deposits
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities	2,494	4,990
Time Deposits \| Short-Term Investments
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, maturities from 1-90 days	497	2,243
Held-to-maturity securities, maturities from 91-360 days	1,199	1,699
Time Deposits \| Long-Term Investments
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, maturities over 360 days	798	1,048
Fixed Income Bonds
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities	3,401	3,513
Fixed Income Bonds \| Short-Term Investments
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, maturities less than 1 year	654	353
Fixed Income Bonds \| Long-Term Investments
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, remaining maturities from 1-3 years	$ 2,747	$ 3,160

Held-To-Maturity Securities, Debt Maturities, 1 To 90 Days, Net Carrying Amount

No definition available.

Name:	astc_HeldToMaturitySecuritiesDebtMaturities1To90DaysNetCarryingAmount
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, 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

Held-to-maturity Securities, Debt Maturities, after One Through Three Years, Net Carrying Amount

+ References

No definition available.

+ Details

Name:	astc_HeldtomaturitySecuritiesDebtMaturitiesafterOneThroughThreeYearsNetCarryingAmount
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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=65884222&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27232-111563

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66010992&loc=d3e26610-111562

+ Details

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

- Definition

Amount of debt and equity financial instruments classified as either held-to-maturity or available-for-sale.

+ References

No definition available.

+ Details

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

- Definition

Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27232-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=65884222&loc=d3e22054-111558

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27232-111563

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.6)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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

- Definition

Carrying amount of debt securities accounted for as held-to-maturity, net of adjustments including, but not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized, and fair value hedge accounting adjustments, maturing in the next fiscal year following the latest fiscal year.

+ References

+ Details

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

- Details

Name:	us-gaap_BalanceSheetLocationAxis=us-gaap_ShortTermInvestmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BalanceSheetLocationAxis=astc_LongTermInvestmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=astc_MutualFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_BankTimeDepositsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_FixedIncomeInvestmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: