| Vanguard Total Stock Market Index Fund | Dec 31, 2017 | 37.4M | 3.3B | 2.4% | 
                
                        | Vanguard 500 Index Fund | Dec 31, 2017 | 26.5M | 2.3B | 1.7% | 
                
                        | American Balanced Fund | Jun 30, 2018 | 22.1M | 1.5B | 1.4% | 
                
                        | Fundamental Investors Inc | Jun 30, 2018 | 20.9M | 1.4B | 1.4% | 
                
                        | Growth Fund Of America Inc | Jun 30, 2018 | 18.7M | 1.3B | 1.2% | 
                
                        | SPDR S&P 500 ETF Trust | Jun 30, 2018 | 17.3M | 1.2B | 1.1% | 
                
                        | Capital Income Builder, Inc. | Jun 30, 2018 | 16.3M | 1.1B | 1.1% | 
                
                        | Vanguard Institutional Index Fund-Institutional Index Fund | Dec 31, 2017 | 15.7M | 1.4B | 1.0% | 
                
                        | MFS Series Trust I-MFS Value Fund | Feb 28, 2018 | 14.2M | 1.2B | 0.9% | 
                
                        | Investment Company Of America | Jun 30, 2018 | 13.0M | 892.7M | 0.8% |