

American Century Investment Trust Summary Prospectus and Prospectus Supplement Short Duration Fund
Supplement dated May 15, 2020 n Summary Prospectus and Prospectus dated August 1, 2019

The following replaces the Average Annual Total Returns table on page 4 of the summary prospectus and page 5 of the prospectus:



Average Annual Total Returns For the calendar year ended December 31, 2018	1 year	5 years	10 years	Since Inception	Inception Date
Investor Class Return Before Taxes	1.33%	1.20%	1.87%	—	11/30/2006
Return After Taxes on Distributions	0.30%	0.39%	1.09%	—	11/30/2006
Return After Taxes on Distributions and Sale of Fund Shares	0.78%	0.55%	1.12%	—	11/30/2006
I Class¹ Return Before Taxes	1.43%	1.31%	1.97%	—	04/10/2017
A Class Return Before Taxes	-1.16%	0.49%	1.38%	—	11/30/2006
C Class Return Before Taxes	0.22%	0.20%	0.85%	—	11/30/2006
R Class Return Before Taxes	0.82%	0.72%	1.37%	—	11/30/2006
R5 Class Return Before Taxes	1.53%	1.41%	2.07%	—	11/30/2006
R6 Class Return Before Taxes	1.48%	—	—	1.14%	07/28/2017
Bloomberg Barclays U.S. 1-3 Year Government/Credit Bond Index (reflects no deduction for fees, expenses or taxes)	1.60%	1.03%	1.52%	—	—


¹	Historical performance for the I Class prior to its inception is based on the performance of R5 Class shares. I Class performance has been adjusted to reflect differences in expenses between classes, if applicable.

- Definition

Supplement [Text Block]

+ References

No definition available.

+ Details

Name:	ck0000908406_SupplementTextBlock
Namespace Prefix:	ck0000908406_
Data Type:	nonnum:textBlockItemType
Balance Type:	na
Period Type:	duration

- Definition

If the value is true, then the document is an amendment to previously-filed/accepted document.

+ References

No definition available.

+ Details

Name:	dei_AmendmentFlag
Namespace Prefix:	dei_
Data Type:	xbrli:booleanItemType
Balance Type:	na
Period Type:	duration

- Definition

The date the document was made available and submitted, in CCYY-MM-DD format. The date of submission, date of acceptance by the recipient, and the document effective date are all potentially different.

+ References

No definition available.

+ Details

Name:	dei_DocumentCreationDate
Namespace Prefix:	dei_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

The date when a document, upon receipt and acceptance, becomes officially effective, in CCYY-MM-DD format. Usually it is a system-assigned date time value, but it may be declared by the submitter in some cases.

+ References

No definition available.

+ Details

Name:	dei_DocumentEffectiveDate
Namespace Prefix:	dei_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

The end date of the period reflected on the cover page if a periodic report. For all other reports and registration statements containing historical data, it is the date up through which that historical data is presented. If there is no historical data in the report, use the filing date. The format of the date is CCYY-MM-DD.

+ References

No definition available.

+ Details

Name:	dei_DocumentPeriodEndDate
Namespace Prefix:	dei_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word "Other".

+ References

No definition available.

+ Details

Name:	dei_DocumentType
Namespace Prefix:	dei_
Data Type:	dei:submissionTypeItemType
Balance Type:	na
Period Type:	duration

- Definition

A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation 12B
-Number 240
-Section 12b
-Subsection 1

+ Details

Name:	dei_EntityCentralIndexKey
Namespace Prefix:	dei_
Data Type:	dei:centralIndexKeyItemType
Balance Type:	na
Period Type:	duration

- Definition

The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation 12B
-Number 240
-Section 12b
-Subsection 1

+ Details

Name:	dei_EntityRegistrantName
Namespace Prefix:	dei_
Data Type:	xbrli:normalizedStringItemType
Balance Type:	na
Period Type:	duration

- Definition

Return Before Taxes.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form
-Number N-1A
-Chapter A
-Section 4
-Subsection b
-Paragraph 2
-Subparagraph instructions
-Clause 4

+ Details

Name:	rr_AverageAnnualReturnInceptionDate
Namespace Prefix:	rr_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

This item represents Average Anuual Total Returns. If a Multiple Class Fund offers a Class in the prospectus that converts into another Class after a stated period, compute average annual total returns in the table by using the returns of the other Class for the period after conversion.

+ References