Oberweis Global Opportunities Fund Oberweis Micro-Cap Fund Oberweis Small-Cap Opportunities Fund Oberweis International Opportunities Fund Oberweis China Opportunities Fund Oberweis Focused International Growth Fund Investor Class Institutional Class Investor Class Institutional Class Investor Class Institutional Class Investor Class Institutional Class Investor Class Institutional Class Institutional Class Small-sized Company Risk [Member] Risks Associated with Non-U.S. Companies [Member] Equity Securities Risk [Member] Micro-Cap Risk [Member] Emerging Market Risks [Member] Risks Associated with Chinese Companies [Member] Government Relationships Risk [Member] Equity-linked Certificates Risk [Member] RMB Currency Risk [Member] Shanghai-Hong Kong Stock Connect Program (Stock Connect) Risk [Member] Geographic Concentration Risk [Member] Currency Risk [Member] Financials Sector Risk [Member] Non-Diversification Risk [Member] Technology Sector Risk [Member] Healthcare Sector Risk [Member] Industrials Sector Risk [Member] Investment Style Risk [Member] Portfolio Turnover Risk [Member] MSCI EAFE Index (reflects no deduction for fees, expenses or taxes) MSCI ACWI Small Cap Index (reflects no deduction for fees, expenses or taxes) S&P 500 Index (reflects no deduction for fees, expenses or taxes) Russell Microcap Growth Index (reflects no deduction for fees, expenses or taxes) Russell 2000 Growth Index (reflects no deduction for fees, expenses or taxes) MSCI World EX US Small Cap Growth Index (reflects no deduction for fees, expenses or taxes) MSCI China Net Index (reflects no deduction for fees, expenses or taxes) C000042583 Member Shanghai Hong Kong Stock Connect Program Stock Connect Risk Member C000247124 Member Non Diversification Risk Member Financials Sector Risk Member C000028299 Member Investment Style Risk Member C000186091 Member Technology Sector Risk Member index_ Russell_ Microcap_ Growth_ Index_reflects_no_deduction_for_fees_expenses_or_taxes Member C000028301 Member Emerging Market Risks Member Geographic Concentration Risks Member C000186089 Member C000182411 Member S000010232 Member S000075665 Member C000234915 Member S000010230 Member Micro Cap Risk Member Portfolio Turnover Risk Member Currency Risk Member C000028300 Member index_ Russell_2000_ Growth_ Index_reflects_no_deduction_for_fees_expenses_or_taxes Member Equity Securities Risk Member Risks Associated With Chinese Companies Member RMBCurrency Risk Member index_ MSCI_ ACWI_ Small_ Cap_ Index_reflects_no_deduction_for_fees_expenses_or_taxes Member S000010231 Member Government Relationships Risk Member index_ MSCI_ World_ EX_ US_ Small_ Cap_ Growth_ Index_reflects_no_deduction_for_fees_expenses_or_taxes Member C000186090 Member S000010233 Member Healthcare Sector Risk Member C000028302 Member index_ SP_500_ Index_reflects_no_deduction_for_fees_expenses_or_taxes Member index_ MSCI_ China_ Net_ Index_reflects_no_deduction_for_fees_expenses_or_taxes Member Smallsized Company Risk Member Risks Associated With Non USCompanies Member Equitylinked Certificates Risk Member Industrials Sector Risk Member S000015622 Member index_ MSCI_ EAFE_ Index_reflects_no_deduction_for_fees_expenses_or_taxes Member