v3.24.4
Average Annual Total Returns
 12 Months Ended 60 Months Ended 82 Months Ended 117 Months Ended 120 Months Ended
Aug. 31, 2024
Dec. 31, 2023
Dec. 31, 2023
Dec. 31, 2023
Dec. 31, 2023
 [1]
Dec. 31, 2023
Schwab Short-Term Bond Index Fund            
Prospectus [Line Items]            
Average Annual Return, Label [Optional Text] Before taxes          
Average Annual Return, Percent   4.78% 1.43% 1.34%    
Performance Inception Date Feb. 23, 2017          
Schwab Short-Term Bond Index Fund | After Taxes on Distributions            
Prospectus [Line Items]            
Average Annual Return, Label [Optional Text] After taxes on distributions          
Average Annual Return, Percent   3.43% 0.62% 0.53%    
Schwab Short-Term Bond Index Fund | After Taxes on Distributions and Sales            
Prospectus [Line Items]            
Average Annual Return, Label [Optional Text] After taxes on distributions and sale of shares          
Average Annual Return, Percent   2.81% 0.76% 0.68%    
Schwab Treasury Inflation Protected Securities Index Fund            
Prospectus [Line Items]            
Average Annual Return, Label [Optional Text] Before taxes          
Average Annual Return, Percent   3.78% 3.04%     2.30%
Schwab Treasury Inflation Protected Securities Index Fund | After Taxes on Distributions            
Prospectus [Line Items]            
Average Annual Return, Label [Optional Text] After taxes on distributions          
Average Annual Return, Percent   2.47% 1.53%     1.12%
Schwab Treasury Inflation Protected Securities Index Fund | After Taxes on Distributions and Sales            
Prospectus [Line Items]            
Average Annual Return, Label [Optional Text] After taxes on distributions and sale of shares          
Average Annual Return, Percent   2.22% 1.73%     1.27%
Schwab U.S. Aggregate Bond Index Fund            
Prospectus [Line Items]            
Average Annual Return, Label [Optional Text] Before taxes          
Average Annual Return, Percent   5.44% 0.97% 1.10%    
Performance Inception Date Feb. 23, 2017          
Schwab U.S. Aggregate Bond Index Fund | After Taxes on Distributions            
Prospectus [Line Items]            
Average Annual Return, Label [Optional Text] After taxes on distributions          
Average Annual Return, Percent   4.04% (0.10%) 0.01%    
Schwab U.S. Aggregate Bond Index Fund | After Taxes on Distributions and Sales            
Prospectus [Line Items]            
Average Annual Return, Label [Optional Text] After taxes on distributions and sale of shares          
Average Annual Return, Percent   3.19% 0.31% 0.39%    
Schwab Tax-Free Bond Fund            
Prospectus [Line Items]            
Average Annual Return, Label [Optional Text] Before taxes          
Average Annual Return, Percent   5.67% 1.77%     2.28%
Schwab Tax-Free Bond Fund | After Taxes on Distributions            
Prospectus [Line Items]            
Average Annual Return, Label [Optional Text] After taxes on distributions          
Average Annual Return, Percent   5.67% 1.71%     2.17%
Schwab Tax-Free Bond Fund | After Taxes on Distributions and Sales            
Prospectus [Line Items]            
Average Annual Return, Label [Optional Text] After taxes on distributions and sale of shares          
Average Annual Return, Percent   4.66% 1.89%     2.27%
Schwab California Tax-Free Bond Fund            
Prospectus [Line Items]            
Average Annual Return, Label [Optional Text] Before taxes          
Average Annual Return, Percent   5.20% 1.57%     2.28%
Schwab California Tax-Free Bond Fund | After Taxes on Distributions            
Prospectus [Line Items]            
Average Annual Return, Label [Optional Text] After taxes on distributions          
Average Annual Return, Percent   5.20% 1.48%     2.14%
Schwab California Tax-Free Bond Fund | After Taxes on Distributions and Sales            
Prospectus [Line Items]            
Average Annual Return, Label [Optional Text] After taxes on distributions and sale of shares          
Average Annual Return, Percent   4.21% 1.69%     2.25%
Schwab Opportunistic Municipal Bond Fund            
Prospectus [Line Items]            
Average Annual Return, Label [Optional Text] Before taxes          
Average Annual Return, Percent   9.23% 1.33%   3.43%  
Performance Inception Date Mar. 31, 2014          
Schwab Opportunistic Municipal Bond Fund | After Taxes on Distributions            
Prospectus [Line Items]            
Average Annual Return, Label [Optional Text] After taxes on distributions          
Average Annual Return, Percent   9.23% 1.25%   3.24%  
Schwab Opportunistic Municipal Bond Fund | After Taxes on Distributions and Sales            
Prospectus [Line Items]            
Average Annual Return, Label [Optional Text] After taxes on distributions and sale of shares          
Average Annual Return, Percent   8.23% 1.90%   3.50%  
Bloomberg US Aggregate Bond Index            
Prospectus [Line Items]            
Average Annual Return, Label [Optional Text] Bloomberg US Aggregate Bond Index          
Average Annual Return, Percent   5.53% 1.10% 1.25%   1.81%
Bloomberg US Government/Credit 1-5 Year Index            
Prospectus [Line Items]            
Average Annual Return, Label [Optional Text] Bloomberg US Government/Credit 1-5 Year Index          
Average Annual Return, Percent   4.89% 1.54% 1.45%    
Bloomberg US Treasury Inflation-Linked Bond Index (Series-L)            
Prospectus [Line Items]            
Average Annual Return, Label [Optional Text] Bloomberg US Treasury Inflation-Linked Bond Index (Series-L)          
Average Annual Return, Percent   3.90% 3.15%     2.42%
Bloomberg Municipal Bond Index            
Prospectus [Line Items]            
Average Annual Return, Label [Optional Text] Bloomberg Municipal Bond Index          
Average Annual Return, Percent   6.40% 2.25%   2.77% 3.03%
Bloomberg Municipal 3-15 Year Blend Index            
Prospectus [Line Items]            
Average Annual Return, Label [Optional Text] Bloomberg Municipal 3-15 Year Blend Index          
Average Annual Return, Percent   5.45% 2.28%     2.77%
Bloomberg California Municipal 3-15 Year Blend Index            
Prospectus [Line Items]            
Average Annual Return, Label [Optional Text] Bloomberg California Municipal 3-15 Year Blend Index          
Average Annual Return, Percent [2]   5.34% [3]     [3]
S&P California AMT-Free Municipal Bond Index            
Prospectus [Line Items]            
Average Annual Return, Label [Optional Text] S&P California AMT-Free Municipal Bond Index          
Average Annual Return, Percent   5.64% 2.10%     3.00%
[1] Inception of the Predecessor Fund.
[2] The Bloomberg California Municipal 3-15 Year Blend Index was established effective January 1, 2020.
[3] Information not available to the fund.