v3.26.3
Average Annual Total Returns
 12 Months Ended 60 Months Ended 63 Months Ended 94 Months Ended 96 Months Ended 112 Months Ended 113 Months Ended 117 Months Ended 120 Months Ended
Nov. 13, 2026
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
FAF Trust MM Prospectus Class A Member | Government Obligations Fund Class A                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] Government Obligations Fund                  
Average Annual Return, Percent   3.60% 2.71%             1.65%
Performance Inception Date Sep. 24, 2001                  
FAF Trust MM Prospectus Class A Member | Retail Prime Obligations Fund Class A                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] Retail Prime Obligations Fund                  
Average Annual Return, Percent   3.69% 2.82%         1.91%    
Performance Inception Date Jul. 18, 2016                  
FAF Trust MM Prospectus Class A Member | Retail Tax Free Obligations Fund Class A                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] [1] Retail Tax Free Obligations Fund2                  
Average Annual Return, Percent [1]   2.04% 1.58%             0.97%
Performance Inception Date [1] Sep. 24, 2001                  
FAF Trust MM Prospectus Class A Member | Treasury Obligations Fund Class A                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] Treasury Obligations Fund                  
Average Annual Return, Percent   3.59% 2.74%             1.66%
Performance Inception Date Sep. 24, 2001                  
FAF Trust MM Prospectus Class A Member | U.S. Treasury Money Market Fund Class A                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] U.S. Treasury Money Market Fund                  
Average Annual Return, Percent   3.54% 2.67%             1.62%
Performance Inception Date Oct. 25, 2004                  
FAF Trust MM Prospectus Class D Member | Government Obligations Fund Class D                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] Government Obligations Fund                  
Average Annual Return, Percent   3.76% 2.82%             1.75%
Performance Inception Date Jan. 21, 1995                  
FAF Trust MM Prospectus Class D Member | Treasury Obligations Fund Class D                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] Treasury Obligations Fund                  
Average Annual Return, Percent   3.75% 2.83%             1.76%
Performance Inception Date Oct. 04, 1993                  
FAF Trust MM Prospectus Class D Member | U.S. Treasury Money Market Fund Class D                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] U.S. Treasury Money Market Fund                  
Average Annual Return, Percent   3.70% 2.78%             1.72%
Performance Inception Date Oct. 25, 2004                  
FAF Trust MM Prospectus Class P Member | Government Obligations Fund Class P                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] Government Obligations Fund                  
Average Annual Return, Percent   4.22% 3.17%     2.50%        
Performance Inception Date Dec. 18, 2017                  
FAF Trust MM Prospectus Class P Member | Treasury Obligations Fund Class P                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] Treasury Obligations Fund                  
Average Annual Return, Percent   4.20% 3.18%     2.50%        
Performance Inception Date Dec. 18, 2017                  
FAF Trust MM Prospectus Class T Member | Government Obligations Fund Class T                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] Government Obligations Fund                  
Average Annual Return, Percent   3.96% 2.97% 2.81%            
Performance Inception Date Sep. 18, 2020                  
FAF Trust MM Prospectus Class T Member | Institutional Prime Obligations Fund Class T                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] [2] Institutional Prime Obligations Fund2                  
Average Annual Return, Percent [2]   3.98% 3.06%             2.02%
Performance Inception Date [2] Sep. 24, 2001                  
FAF Trust MM Prospectus Class T Member | Retail Prime Obligations Fund Class T                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] Retail Prime Obligations Fund                  
Average Annual Return, Percent   4.05% 3.08%         2.16%    
Performance Inception Date Jul. 18, 2016                  
FAF Trust MM Prospectus Class T Member | Retail Tax Free Obligations Fund Class T                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] Retail Tax Free Obligations Fund                  
Average Annual Return, Percent   2.41% 1.84% 1.74%            
Performance Inception Date Sep. 18, 2020                  
FAF Trust MM Prospectus Class T Member | Treasury Obligations Fund Class T                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] Treasury Obligations Fund                  
Average Annual Return, Percent   3.95% 2.98%             2.82%
Performance Inception Date Sep. 18, 2020                  
FAF Trust MM Prospectus Class T Member | U.S. Treasury Money Market Fund Class T                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] U.S. Treasury Money Market Fund                  
Average Annual Return, Percent   3.90% 2.93%             2.77%
Performance Inception Date Sep. 18, 2020                  
FAF Trust MM Prospectus Class U Member | Government Obligations Fund Class U                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] Government Obligations Fund - Class U                  
Average Annual Return, Percent   4.25% 3.19%   2.56%          
Performance Inception Date Feb. 26, 2018                  
FAF Trust MM Prospectus Class V Member | Government Obligations Fund Class V                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] Government Obligations Fund                  
Average Annual Return, Percent   4.07% 3.05%             1.98%
Performance Inception Date Mar. 31, 2006                  
FAF Trust MM Prospectus Class V Member | Institutional Prime Obligations Fund Class V                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] [3] Institutional Prime Obligations Fund2                  
Average Annual Return, Percent [3]   4.09% 3.14%             2.10%
Performance Inception Date [3] Mar. 31, 2006                  
FAF Trust MM Prospectus Class V Member | Retail Prime Obligations Fund Class V                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] Retail Prime Obligations Fund                  
Average Annual Return, Percent   4.15% 3.16%         2.25%    
Performance Inception Date Jul. 18, 2016                  
FAF Trust MM Prospectus Class V Member | Retail Tax Free Obligations Fund Class V                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] [4] Retail Tax Free Obligations Fund2                  
Average Annual Return, Percent [4]   2.50% 1.92%             1.30%
Performance Inception Date [4] Mar. 31, 2006                  
FAF Trust MM Prospectus Class V Member | Treasury Obligations Fund Class V                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] Treasury Obligations Fund                  
Average Annual Return, Percent   4.06% 3.06%             1.98%
Performance Inception Date Mar. 31, 2006                  
FAF Trust MM Prospectus Class V Member | U.S. Treasury Money Market Fund Class V                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] U.S. Treasury Money Market Fund                  
Average Annual Return, Percent   4.01% 3.01%             1.94%
Performance Inception Date Mar. 31, 2006                  
FAF Trust MM Prospectus Class X Member | Government Obligations Fund Class X                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] Government Obligations Fund                  
Average Annual Return, Percent   4.23% 3.18%           2.17%  
Performance Inception Date Apr. 05, 2016                  
FAF Trust MM Prospectus Class X Member | Retail Prime Obligations Fund Class X                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] Retail Prime Obligations Fund                  
Average Annual Return, Percent   4.32% 3.29%       2.42%      
Performance Inception Date Sep. 08, 2016                  
FAF Trust MM Prospectus Class X Member | Treasury Obligations Fund Class X                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] Treasury Obligations Fund                  
Average Annual Return, Percent   4.22% 3.19%           2.17%  
Performance Inception Date Apr. 05, 2016                  
FAF Trust MM Prospectus Class X Member | U.S. Treasury Money Market Fund Class X                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] U.S. Treasury Money Market Fund                  
Average Annual Return, Percent   3.54% 2.67%             1.62%
Performance Inception Date Oct. 25, 2004                  
FAF Trust MM Prospectus Class Y Member | Government Obligations Fund Class Y                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] Government Obligations Fund                  
Average Annual Return, Percent   3.91% 2.94%             1.86%
Performance Inception Date Mar. 01, 1990                  
FAF Trust MM Prospectus Class Y Member | Institutional Prime Obligations Fund Class Y                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] [5] Institutional Prime Obligations Fund2                  
Average Annual Return, Percent [5]   3.94% 3.03%             1.98%
Performance Inception Date [5] Mar. 01, 1990                  
FAF Trust MM Prospectus Class Y Member | Retail Prime Obligations Fund Class Y                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] Retail Prime Obligations Fund                  
Average Annual Return, Percent   4.00% 3.05%         2.12%    
Performance Inception Date Jul. 18, 2016                  
FAF Trust MM Prospectus Class Y Member | Retail Tax Free Obligations Fund Class Y                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] [6] Retail Tax Free Obligations Fund2                  
Average Annual Return, Percent [6]   2.35% 1.80%             1.18%
Performance Inception Date [6] Jan. 09, 1995                  
FAF Trust MM Prospectus Class Y Member | Treasury Obligations Fund Class Y                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] Treasury Obligations Fund                  
Average Annual Return, Percent   3.90% 2.95%             1.86%
Performance Inception Date Jan. 24, 1995                  
FAF Trust MM Prospectus Class Y Member | U.S. Treasury Money Market Fund Class Y                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] U.S. Treasury Money Market Fund                  
Average Annual Return, Percent   3.86% 2.90%             1.82%
Performance Inception Date Oct. 25, 2004                  
FAF Trust MM Prospectus Class Z Member | Government Obligations Fund Class Z                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] Government Obligations Fund                  
Average Annual Return, Percent   4.19% 3.14%             2.08%
Performance Inception Date Dec. 01, 2003                  
FAF Trust MM Prospectus Class Z Member | Institutional Prime Obligations Fund Class Z                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] [7] Institutional Prime Obligations Fund2                  
Average Annual Return, Percent [7]   4.19% 3.23%             2.21%
Performance Inception Date [7] Aug. 01, 2003                  
FAF Trust MM Prospectus Class Z Member | Retail Prime Obligations Fund Class Z                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] Retail Prime Obligations Fund                  
Average Annual Return, Percent   4.26% 3.24%         2.33%    
Performance Inception Date Jul. 18, 2016                  
FAF Trust MM Prospectus Class Z Member | Retail Tax Free Obligations Fund Class Z                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] [8] Retail Tax Free Obligations Fund2                  
Average Annual Return, Percent [8]   2.60% 1.99%             1.38%
Performance Inception Date [8] Dec. 01, 2003                  
FAF Trust MM Prospectus Class Z Member | Treasury Obligations Fund Class Z                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] Treasury Obligations Fund                  
Average Annual Return, Percent   4.17% 3.16%             2.08%
Performance Inception Date Dec. 01, 2003                  
FAF Trust MM Prospectus Class Z Member | U.S. Treasury Money Market Fund Class Z                    
Prospectus [Line Items]                    
Average Annual Return, Label [Optional Text] U.S. Treasury Money Market Fund                  
Average Annual Return, Percent   4.11% 3.09%             2.02%
Performance Inception Date Oct. 25, 2004                  
[1] Prior to October 14, 2016, the fund was named Tax Free Obligations Fund.
[2] Prior to October 14, 2016, the fund was named Prime Obligations Fund.
[3] Prior to October 14, 2016, the fund was named Prime Obligations Fund.
[4] Prior to October 14, 2016, the fund was named Tax Free Obligations Fund.
[5] Prior to October 14, 2016, the fund was named Prime Obligations Fund.
[6] Prior to October 14, 2016, the fund was named Tax Free Obligations Fund.
[7] Prior to October 14, 2016, the fund was named Prime Obligations Fund.
[8] Prior to October 14, 2016, the fund was named Tax Free Obligations Fund.