Shareholder Report, Average Annual Return (Details)	12 Months Ended			33 Months Ended		60 Months Ended	92 Months Ended		120 Months Ended
	Dec. 31, 2024	[5]	Dec. 31, 2024	Dec. 31, 2024	[6]	Dec. 31, 2024	Dec. 31, 2024		Dec. 31, 2024
Oberweis Micro-Cap Fund | Investor Class [Member]
Average Annual Return [Line Items]
Line Graph and Table Measure Name			OBMCX
Average Annual Return, Percent			22.87%			21.07%			16.78%
Oberweis Micro-Cap Fund | Institutional Class [Member]
Average Annual Return [Line Items]
Line Graph and Table Measure Name			OMCIX
Average Annual Return, Percent			23.16%			21.39%	16.88%	[1]
Oberweis Small-Cap Opportunities Fund | Investor Class [Member]
Average Annual Return [Line Items]
Line Graph and Table Measure Name			OBSOX
Average Annual Return, Percent			16.14%			17.84%			14.09%
Oberweis Small-Cap Opportunities Fund | Institutional Class [Member]
Average Annual Return [Line Items]
Line Graph and Table Measure Name			OBSIX
Average Annual Return, Percent			16.40%			18.12%	15.36%	[2]
Oberweis Global Opportunities Fund | Investor Class [Member]
Average Annual Return [Line Items]
Line Graph and Table Measure Name			OBEGX
Average Annual Return, Percent			10.72%			10.16%			8.14%
Oberweis Global Opportunities Fund | Institutional Class [Member]
Average Annual Return [Line Items]
Line Graph and Table Measure Name			OBGIX
Average Annual Return, Percent			11.01%			10.44%	8.08%	[3]
Oberweis China Opportunities Fund | Investor Class [Member]
Average Annual Return [Line Items]
Line Graph and Table Measure Name			OBCHX
Average Annual Return, Percent			7.29%			(1.65%)			2.48%
Oberweis China Opportunities Fund | Institutional Class [Member]
Average Annual Return [Line Items]
Line Graph and Table Measure Name			OCHIX
Average Annual Return, Percent			7.61%			(1.41%)	3.01%	[4]
Oberweis International Opportunities Fund | Investor Class [Member]
Average Annual Return [Line Items]
Line Graph and Table Measure Name			OBIOX
Average Annual Return, Percent			7.54%			3.26%			5.24%
Oberweis International Opportunities Fund | Institutional Class [Member]
Average Annual Return [Line Items]
Line Graph and Table Measure Name			OBIIX
Average Annual Return, Percent	8.41%		7.70%
Oberweis Focused International Growth Fund | Institutional Class [Member]
Average Annual Return [Line Items]
Line Graph and Table Measure Name			OFIGX
Average Annual Return, Percent			11.79%	0.25%
Standard & Poor's 500 Index [Member]
Average Annual Return [Line Items]
Line Graph and Table Measure Name			S&P 500 Index
Average Annual Return, Percent			25.02%			14.53%	14.45%	[1],[2]	13.10%
Russell Microcap Growth Index [Member]
Average Annual Return [Line Items]
Line Graph and Table Measure Name			Russell Microcap Growth Index
Average Annual Return, Percent			21.91%			5.72%	6.07%	[1]	5.30%
Russell 2000 Growth Index [Member]
Average Annual Return [Line Items]
Line Graph and Table Measure Name			Russell 2000 Growth Index
Average Annual Return, Percent			15.15%			6.86%	8.34%	[2]	8.09%
MSCI ACWI Small-Cap Index [Member]
Average Annual Return [Line Items]
Line Graph and Table Measure Name			MSCI ACWI Small-Cap Index
Average Annual Return, Percent			7.66%			6.68%	7.07%	[3]	7.26%
MSCI EAFE Index [Member]
Average Annual Return [Line Items]
Line Graph and Table Measure Name			MSCI EAFE Index
Average Annual Return, Percent	4.93%		3.82%	4.08%		4.73%	5.49%	[3]	5.20%
MSCI China Net Index [Member]
Average Annual Return [Line Items]
Line Graph and Table Measure Name			MSCI China Net Index
Average Annual Return, Percent			19.42%			(3.44%)	1.46%	[4]	1.88%
MSCI World ex-US Small Cap Growth Index [Member]
Average Annual Return [Line Items]
Line Graph and Table Measure Name			MSCI World ex-US Small Cap Growth Index
Average Annual Return, Percent	3.92%		2.57%			2.06%			5.67%

[1] Since the inception of OMCIX on May 1, 2017.

[2] Since the inception of OBSIX on May 1, 2017.

[3] Since the inception of OBGIX on May 1, 2017.

[4] Since the inception of OCHIX on May 1, 2017.

[5] Since the inception of OBIIX on December 22, 2023.

[6] Since the inception of OFIGX on April 1, 2022.