Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

NORTHERN FUNDS

Prospectus Date

rr_ProspectusDate

Jul. 31, 2011

Supplement [Text Block]

cik0000916620_SupplementTextBlock

PROSPECTUS SUPPLEMENT

NORTHERN FUNDS

EQUITY INDEX FUNDS

SUPPLEMENT DATED AUGUST 29, 2011 (AS REVISED AND RESTATED OCTOBER 26, 2011)

TO PROSPECTUS DATED JULY 31, 2011

Northern Trust Investments, Inc. is scheduled to increase the expense reimbursements it provides to certain Northern Funds effective as of January 1, 2012. This increase in expense reimbursements will have the effect of reducing the Total Annual Fund Operating Expenses paid by investors. The following chart illustrates the increase in expense reimbursements:

Fund	Total Annual Fund Operating Expenses After Expense Reimbursement (if any)	Operating Expense Reduction	Total Annual Fund Operating Expenses After Expense Reimbursement Effective 1/1/2012
Emerging Markets Equity Index	0.72%	-0.42%	0.30%
Global Real Estate Index	0.65%	-0.15%	0.50%
Global Sustainability Index	0.65%	-0.35%	0.30%
International Equity Index	0.45%	-0.20%	0.25%
Mid Cap Index	0.30%	-0.15%	0.15%
Small Cap Index	0.35%	-0.20%	0.15%
Stock Index	0.25%	-0.15%	0.10%

These new contractual expense reimbursement arrangements are expected to continue from implementation until at least December 31, 2012.

Please retain this Supplement with your Prospectus for future reference.

NORTHERN EMERGING MARKETS EQUITY INDEX FUND

Risk/Return:

rr_RiskReturnAbstract

Supplement [Text Block]

cik0000916620_SupplementTextBlock

PROSPECTUS SUPPLEMENT

NORTHERN FUNDS

EQUITY INDEX FUNDS

SUPPLEMENT DATED AUGUST 29, 2011 (AS REVISED AND RESTATED OCTOBER 26, 2011)

TO PROSPECTUS DATED JULY 31, 2011

Northern Trust Investments, Inc. is scheduled to increase the expense reimbursements it provides to certain Northern Funds effective as of January 1, 2012. This increase in expense reimbursements will have the effect of reducing the Total Annual Fund Operating Expenses paid by investors. The following chart illustrates the increase in expense reimbursements:

Fund	Total Annual Fund Operating Expenses After Expense Reimbursement (if any)	Operating Expense Reduction	Total Annual Fund Operating Expenses After Expense Reimbursement Effective 1/1/2012
Emerging Markets Equity Index	0.72%	-0.42%	0.30%

These new contractual expense reimbursement arrangements are expected to continue from implementation until at least December 31, 2012.

Please retain this Supplement with your Prospectus for future reference.

NORTHERN GLOBAL REAL ESTATE INDEX FUND

Risk/Return:

rr_RiskReturnAbstract

Supplement [Text Block]

cik0000916620_SupplementTextBlock

PROSPECTUS SUPPLEMENT

NORTHERN FUNDS

EQUITY INDEX FUNDS

SUPPLEMENT DATED AUGUST 29, 2011 (AS REVISED AND RESTATED OCTOBER 26, 2011)

TO PROSPECTUS DATED JULY 31, 2011

Northern Trust Investments, Inc. is scheduled to increase the expense reimbursements it provides to certain Northern Funds effective as of January 1, 2012. This increase in expense reimbursements will have the effect of reducing the Total Annual Fund Operating Expenses paid by investors. The following chart illustrates the increase in expense reimbursements:

Fund	Total Annual Fund Operating Expenses After Expense Reimbursement (if any)	Operating Expense Reduction	Total Annual Fund Operating Expenses After Expense Reimbursement Effective 1/1/2012
Global Real Estate Index	0.65%	-0.15%	0.50%

These new contractual expense reimbursement arrangements are expected to continue from implementation until at least December 31, 2012.

Please retain this Supplement with your Prospectus for future reference.

NORTHERN GLOBAL SUSTAINABILITY INDEX FUND

Risk/Return:

rr_RiskReturnAbstract

Supplement [Text Block]

cik0000916620_SupplementTextBlock

PROSPECTUS SUPPLEMENT

NORTHERN FUNDS

EQUITY INDEX FUNDS

SUPPLEMENT DATED AUGUST 29, 2011 (AS REVISED AND RESTATED OCTOBER 26, 2011)

TO PROSPECTUS DATED JULY 31, 2011

Northern Trust Investments, Inc. is scheduled to increase the expense reimbursements it provides to certain Northern Funds effective as of January 1, 2012. This increase in expense reimbursements will have the effect of reducing the Total Annual Fund Operating Expenses paid by investors. The following chart illustrates the increase in expense reimbursements:

Fund	Total Annual Fund Operating Expenses After Expense Reimbursement (if any)	Operating Expense Reduction	Total Annual Fund Operating Expenses After Expense Reimbursement Effective 1/1/2012
Global Sustainability Index	0.65%	-0.35%	0.30%

These new contractual expense reimbursement arrangements are expected to continue from implementation until at least December 31, 2012.

Please retain this Supplement with your Prospectus for future reference.

NORTHERN INTERNATIONAL EQUITY INDEX FUND

Risk/Return:

rr_RiskReturnAbstract

Supplement [Text Block]

cik0000916620_SupplementTextBlock

PROSPECTUS SUPPLEMENT

NORTHERN FUNDS

EQUITY INDEX FUNDS

SUPPLEMENT DATED AUGUST 29, 2011 (AS REVISED AND RESTATED OCTOBER 26, 2011)

TO PROSPECTUS DATED JULY 31, 2011

Northern Trust Investments, Inc. is scheduled to increase the expense reimbursements it provides to certain Northern Funds effective as of January 1, 2012. This increase in expense reimbursements will have the effect of reducing the Total Annual Fund Operating Expenses paid by investors. The following chart illustrates the increase in expense reimbursements:

Fund	Total Annual Fund Operating Expenses After Expense Reimbursement (if any)	Operating Expense Reduction	Total Annual Fund Operating Expenses After Expense Reimbursement Effective 1/1/2012
International Equity Index	0.45%	-0.20%	0.25%

These new contractual expense reimbursement arrangements are expected to continue from implementation until at least December 31, 2012.

Please retain this Supplement with your Prospectus for future reference.

NORTHERN MID CAP INDEX FUND

Risk/Return:

rr_RiskReturnAbstract

Supplement [Text Block]

cik0000916620_SupplementTextBlock

PROSPECTUS SUPPLEMENT

NORTHERN FUNDS

EQUITY INDEX FUNDS

SUPPLEMENT DATED AUGUST 29, 2011 (AS REVISED AND RESTATED OCTOBER 26, 2011)

TO PROSPECTUS DATED JULY 31, 2011

Northern Trust Investments, Inc. is scheduled to increase the expense reimbursements it provides to certain Northern Funds effective as of January 1, 2012. This increase in expense reimbursements will have the effect of reducing the Total Annual Fund Operating Expenses paid by investors. The following chart illustrates the increase in expense reimbursements:

Fund	Total Annual Fund Operating Expenses After Expense Reimbursement (if any)	Operating Expense Reduction	Total Annual Fund Operating Expenses After Expense Reimbursement Effective 1/1/2012
Mid Cap Index	0.30%	-0.15%	0.15%

These new contractual expense reimbursement arrangements are expected to continue from implementation until at least December 31, 2012.

Please retain this Supplement with your Prospectus for future reference.

NORTHERN SMALL CAP INDEX FUND

Risk/Return:

rr_RiskReturnAbstract

Supplement [Text Block]

cik0000916620_SupplementTextBlock

PROSPECTUS SUPPLEMENT

NORTHERN FUNDS

EQUITY INDEX FUNDS

SUPPLEMENT DATED AUGUST 29, 2011 (AS REVISED AND RESTATED OCTOBER 26, 2011)

TO PROSPECTUS DATED JULY 31, 2011

Northern Trust Investments, Inc. is scheduled to increase the expense reimbursements it provides to certain Northern Funds effective as of January 1, 2012. This increase in expense reimbursements will have the effect of reducing the Total Annual Fund Operating Expenses paid by investors. The following chart illustrates the increase in expense reimbursements:

Fund	Total Annual Fund Operating Expenses After Expense Reimbursement (if any)	Operating Expense Reduction	Total Annual Fund Operating Expenses After Expense Reimbursement Effective 1/1/2012
Small Cap Index	0.35%	-0.20%	0.15%

These new contractual expense reimbursement arrangements are expected to continue from implementation until at least December 31, 2012.

Please retain this Supplement with your Prospectus for future reference.

NORTHERN STOCK INDEX FUND

Risk/Return:

rr_RiskReturnAbstract

Supplement [Text Block]

cik0000916620_SupplementTextBlock

PROSPECTUS SUPPLEMENT

NORTHERN FUNDS

EQUITY INDEX FUNDS

SUPPLEMENT DATED AUGUST 29, 2011 (AS REVISED AND RESTATED OCTOBER 26, 2011)

TO PROSPECTUS DATED JULY 31, 2011

Northern Trust Investments, Inc. is scheduled to increase the expense reimbursements it provides to certain Northern Funds effective as of January 1, 2012. This increase in expense reimbursements will have the effect of reducing the Total Annual Fund Operating Expenses paid by investors. The following chart illustrates the increase in expense reimbursements:

Fund	Total Annual Fund Operating Expenses After Expense Reimbursement (if any)	Operating Expense Reduction	Total Annual Fund Operating Expenses After Expense Reimbursement Effective 1/1/2012
Stock Index	0.25%	-0.15%	0.10%

These new contractual expense reimbursement arrangements are expected to continue from implementation until at least December 31, 2012.

Please retain this Supplement with your Prospectus for future reference.