Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

COLUMBIA FUNDS SERIES TRUST I

Prospectus Date

rr_ProspectusDate

Sep. 01, 2014

Supplement [Text Block]

cfsti2_SupplementTextBlock

Supplement dated January 20, 2015

To the Prospectus, as supplemented, of the following fund:

Fund	Prospectus Dated
Columbia Intermediate Bond Fund	9/1/2014

Effective February 19, 2015 (the Effective Date), the maximum sales charge (load) imposed on purchases (as a percentage of the offering price) of Class A shares is changed from 3.25% to 3.00%.

Accordingly, on the Effective Date, the Fund's prospectus is hereby revised as follows:

The Class A column of the "Shareholder Fees" table in the "Summary of the Fund — Fees and Expenses of the Fund" section is hereby revised as follows:

Shareholder Fees (fees paid directly from your investment)
	Class A
Maximum sales charge (load) imposed on purchases (as a % of offering price)		3.00	%
Maximum deferred sales charge (load) imposed on redemptions (as a % of the lower of the original purchase price or current net asset value)		1.00	%(a)

(a)  This charge is imposed on certain investments of between $1 million and $50 million redeemed within 18 months of purchase, as follows: 1.00% if redeemed within 12 months of purchase, and 0.50% if redeemed more than 12, but less than 18, months after purchase, with certain limited exceptions.

Additionally, the expense Example table for Class A shares (whether or not shares are redeemed) is hereby revised as follows:

	1 year		3 years		5 years		10 years
Class A (whether or not shares are redeemed)	$	390	$	581	$	789	$	1,386

The rest of the section remains the same. 

Columbia Intermediate Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Supplement [Text Block]

cfsti2_SupplementTextBlock

Supplement dated January 20, 2015

To the Prospectus, as supplemented, of the following fund:

Fund	Prospectus Dated
Columbia Intermediate Bond Fund	9/1/2014

Effective February 19, 2015 (the Effective Date), the maximum sales charge (load) imposed on purchases (as a percentage of the offering price) of Class A shares is changed from 3.25% to 3.00%.

Accordingly, on the Effective Date, the Fund's prospectus is hereby revised as follows:

The Class A column of the "Shareholder Fees" table in the "Summary of the Fund — Fees and Expenses of the Fund" section is hereby revised as follows:

Shareholder Fees (fees paid directly from your investment)
	Class A
Maximum sales charge (load) imposed on purchases (as a % of offering price)		3.00	%
Maximum deferred sales charge (load) imposed on redemptions (as a % of the lower of the original purchase price or current net asset value)		1.00	%(a)

(a)  This charge is imposed on certain investments of between $1 million and $50 million redeemed within 18 months of purchase, as follows: 1.00% if redeemed within 12 months of purchase, and 0.50% if redeemed more than 12, but less than 18, months after purchase, with certain limited exceptions.

Additionally, the expense Example table for Class A shares (whether or not shares are redeemed) is hereby revised as follows:

	1 year		3 years		5 years		10 years
Class A (whether or not shares are redeemed)	$	390	$	581	$	789	$	1,386

The rest of the section remains the same. 

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Columbia Intermediate Bond Fund | Class A

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

3.00%

Maximum deferred sales charge (load) imposed on redemptions (as a % of the lower of the original purchase price or current net asset value)

rr_MaximumDeferredSalesChargeOverOther

1.00%

^[1]

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

This charge is imposed on certain investments of between $1 million and $50 million redeemed within 18 months of purchase, as follows: 1.00% if redeemed within 12 months of purchase, and 0.50% if redeemed more than 12, but less than 18, months after purchase, with certain limited exceptions.

1 year

rr_ExpenseExampleYear01

390

3 years

rr_ExpenseExampleYear03

581

5 years

rr_ExpenseExampleYear05

789

10 years

rr_ExpenseExampleYear10

1,386

1 year

rr_ExpenseExampleNoRedemptionYear01

390

3 years

rr_ExpenseExampleNoRedemptionYear03

581

5 years

rr_ExpenseExampleNoRedemptionYear05

789

10 years

rr_ExpenseExampleNoRedemptionYear10

1,386

[1] This charge is imposed on certain investments of between $1 million and $50 million redeemed within 18 months of purchase, as follows: 1.00% if redeemed within 12 months of purchase, and 0.50% if redeemed more than 12, but less than 18, months after purchase, with certain limited exceptions.