In Millions, unless otherwise specified | Fair Value, Inputs, Level 1 [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Inputs, Level 3 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] |
| | | US Government Agencies Debt Securities [Member] | US Government Agencies Debt Securities [Member] | Corporate Debt Securities [Member] | Corporate Debt Securities [Member] | US Government-sponsored Enterprises Debt Securities [Member] | US Government-sponsored Enterprises Debt Securities [Member] | Asset-backed Securities [Member] | Asset-backed Securities [Member] | Municipal Bonds [Member] | Municipal Bonds [Member] | Other Debt Obligations [Member] | Other Debt Obligations [Member] | Auction Rate Securities [Member] | Auction Rate Securities [Member] | Canadian Asset Backed Commercial Paper Restructuring Notes [Member] | Canadian Asset Backed Commercial Paper Restructuring Notes [Member] | | | US Government Agencies Debt Securities [Member] | US Government Agencies Debt Securities [Member] | Corporate Debt Securities [Member] | Corporate Debt Securities [Member] | US Government-sponsored Enterprises Debt Securities [Member] | US Government-sponsored Enterprises Debt Securities [Member] | Asset-backed Securities [Member] | Asset-backed Securities [Member] | Municipal Bonds [Member] | Municipal Bonds [Member] | Other Debt Obligations [Member] | Other Debt Obligations [Member] | Auction Rate Securities [Member] | Auction Rate Securities [Member] | Canadian Asset Backed Commercial Paper Restructuring Notes [Member] | Canadian Asset Backed Commercial Paper Restructuring Notes [Member] | | | US Government Agencies Debt Securities [Member] | US Government Agencies Debt Securities [Member] | Corporate Debt Securities [Member] | Corporate Debt Securities [Member] | US Government-sponsored Enterprises Debt Securities [Member] | US Government-sponsored Enterprises Debt Securities [Member] | Asset-backed Securities [Member] | Asset-backed Securities [Member] | Municipal Bonds [Member] | Municipal Bonds [Member] | Other Debt Obligations [Member] | Other Debt Obligations [Member] | Auction Rate Securities [Member] | Auction Rate Securities [Member] | Canadian Asset Backed Commercial Paper Restructuring Notes [Member] | Canadian Asset Backed Commercial Paper Restructuring Notes [Member] | | | US Government Agencies Debt Securities [Member] | US Government Agencies Debt Securities [Member] | Corporate Debt Securities [Member] | Corporate Debt Securities [Member] | US Government-sponsored Enterprises Debt Securities [Member] | US Government-sponsored Enterprises Debt Securities [Member] | Asset-backed Securities [Member] | Asset-backed Securities [Member] | Municipal Bonds [Member] | Municipal Bonds [Member] | Other Debt Obligations [Member] | Other Debt Obligations [Member] | Auction Rate Securities [Member] | Auction Rate Securities [Member] | Canadian Asset Backed Commercial Paper Restructuring Notes [Member] | Canadian Asset Backed Commercial Paper Restructuring Notes [Member] |