XML 11 R3.htm IDEA: XBRL DOCUMENT v3.7.0.1
Label Element Value
Prospectus: rr_ProspectusTable  
Document Type dei_DocumentType 497
Document Period End Date dei_DocumentPeriodEndDate Jul. 10, 2017
Entity Registrant Name dei_EntityRegistrantName AMERICAN CENTURY GOVERNMENT INCOME TRUST
Central Index Key dei_EntityCentralIndexKey 0000773674
Amendment Flag dei_AmendmentFlag false
Document Creation Date dei_DocumentCreationDate Jul. 10, 2017
Document Effective Date dei_DocumentEffectiveDate Apr. 10, 2017
Prospectus Date rr_ProspectusDate Apr. 10, 2017
American Century Government Income Trust | CAPITAL PRESERVATION FUND  
Prospectus: rr_ProspectusTable  
Supplement [Text Block] ck0000773674_SupplementTextBlock
American Century Government Income Trust
Summary Prospectus and Prospectus Supplement
Capital Preservation Fund
 
Supplement dated July 11, 2017 n Summary Prospectus and Prospectus dated April 10, 2017


The following replaces the Average Annual Total Returns table on page 3 of the summary prospectus and the prospectus:

Average Annual Total Returns
For the calendar year ended December 31, 2016          
1 year
5 years
10 years
Investor Class
0.01%
0.01%
0.60%
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2016
American Century Government Income Trust | CAPITAL PRESERVATION FUND | CAPITAL PRESERVATION FUND INVESTOR CLASS  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Investor Class
1 Year rr_AverageAnnualReturnYear01 0.01%
5 Years rr_AverageAnnualReturnYear05 0.01%
10 Years rr_AverageAnnualReturnYear10 0.60%