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000011 - Document - Risk/Return Summary {Unlabeled} - NORTHERN INSTITUTIONAL U.S. GOVERNMENT PORTFOLIO (Shares)
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000012 - Schedule - Shareholder Fees
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000013 - Schedule - Annual Fund Operating Expenses
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000014 - Schedule - Expense Example {Transposed}
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000015 - Schedule - Expense Example, No Redemption
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000021 - Document - Risk/Return Summary {Unlabeled} - NORTHERN INSTITUTIONAL U.S. GOVERNMENT SELECT PORTFOLIO (Shares)
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000022 - Schedule - Shareholder Fees
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000023 - Schedule - Annual Fund Operating Expenses
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000024 - Schedule - Expense Example {Transposed}
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000033 - Schedule - Annual Fund Operating Expenses
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000038 - Document - Risk/Return Detail {Unlabeled} - NORTHERN INSTITUTIONAL TREASURY PORTFOLIO (SHARES)
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000039 - Disclosure - Risk/Return Detail Data {Elements} - NORTHERN INSTITUTIONAL TREASURY PORTFOLIO (Shares)
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000041 - Document - Risk/Return Summary {Unlabeled} - NORTHERN INSTITUTIONAL U.S. GOVERNMENT PORTFOLIO (Service and Premier Shares)
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000052 - Schedule - Shareholder Fees
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000053 - Schedule - Annual Fund Operating Expenses
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000054 - Schedule - Expense Example {Transposed}
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000064 - Schedule - Expense Example {Transposed}
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000079 - Disclosure - Risk/Return Detail Data {Elements} - NORTHERN INSTITUTIONAL U.S. GOVERNMENT SELECT PORTFOLIO (Williams Capital Shares)
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