Fair Value Measurements - Input Hierarchy of Items Measured at Fair Value on a Recurring Basis (Details) (USD $) | Mar. 31, 2015 | Dec. 31, 2014 |
Automotive [Member] | | |
Derivative Financial Instrument Assets | | |
Derivative financial instruments assets | $1,102,000,000 | $517,000,000 |
Derivative financial instruments liabilities | | |
Derivative financial instruments liabilities | 1,266,000,000 | 713,000,000 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | | |
Cash equivalents - financial instruments | | |
Cash equivalents - financial instruments | 241,000,000 | 206,000,000 |
Marketable securities | | |
Marketable securities | 14,468,000,000 | 17,135,000,000 |
Derivative Financial Instrument Assets | | |
Derivative financial instruments assets | 1,102,000,000 | 517,000,000 |
Total assets at fair value | 15,811,000,000 | 17,858,000,000 |
Derivative financial instruments liabilities | | |
Derivative financial instruments liabilities | 1,266,000,000 | 713,000,000 |
Total liabilities at fair value | 1,266,000,000 | 713,000,000 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | US Treasury and Government [Member] | | |
Cash equivalents - financial instruments | | |
Cash equivalents - financial instruments | 11,000,000 | 64,000,000 |
Marketable securities | | |
Marketable securities | 4,043,000,000 | 6,758,000,000 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | Foreign Government and Agencies [Member] | | |
Cash equivalents - financial instruments | | |
Cash equivalents - financial instruments | 220,000,000 | 122,000,000 |
Marketable securities | | |
Marketable securities | 6,911,000,000 | 7,004,000,000 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | Corporate Debt [Domain] | | |
Cash equivalents - financial instruments | | |
Cash equivalents - financial instruments | 10,000,000 | 20,000,000 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | Corporate Debt [Member] | | |
Marketable securities | | |
Marketable securities | 2,922,000,000 | 2,738,000,000 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | Equities [Member] | | |
Marketable securities | | |
Marketable securities | 270,000,000 | 322,000,000 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | Other marketable securities [Member] | | |
Marketable securities | | |
Marketable securities | 322,000,000 | 313,000,000 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | Cash equivalents - financial instruments [Member] | | |
Input Hierarchy of Items Measured at Fair Value on a Recurring Basis - Footnote Narrative | | |
Par Value Assets Excluded From Fair Value By Input | 3,500,000,000 | 3,300,000,000 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | Cash [Member] | | |
Input Hierarchy of Items Measured at Fair Value on a Recurring Basis - Footnote Narrative | | |
Par Value Assets Excluded From Fair Value By Input | 1,400,000,000 | 1,100,000,000 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | | |
Cash equivalents - financial instruments | | |
Cash equivalents - financial instruments | 0 | 0 |
Marketable securities | | |
Marketable securities | 1,023,000,000 | 1,291,000,000 |
Derivative Financial Instrument Assets | | |
Derivative financial instruments assets | 0 | 0 |
Total assets at fair value | 1,023,000,000 | 1,291,000,000 |
Derivative financial instruments liabilities | | |
Derivative financial instruments liabilities | 0 | 0 |
Total liabilities at fair value | 0 | 0 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | US Treasury and Government [Member] | | |
Cash equivalents - financial instruments | | |
Cash equivalents - financial instruments | 0 | 0 |
Marketable securities | | |
Marketable securities | 753,000,000 | 969,000,000 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Foreign Government and Agencies [Member] | | |
Cash equivalents - financial instruments | | |
Cash equivalents - financial instruments | 0 | 0 |
Marketable securities | | |
Marketable securities | 0 | 0 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Corporate Debt [Domain] | | |
Cash equivalents - financial instruments | | |
Cash equivalents - financial instruments | 0 | 0 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Corporate Debt [Member] | | |
Marketable securities | | |
Marketable securities | 0 | 0 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Equities [Member] | | |
Marketable securities | | |
Marketable securities | 270,000,000 | 322,000,000 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Other marketable securities [Member] | | |
Marketable securities | | |
Marketable securities | 0 | 0 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | | |
Cash equivalents - financial instruments | | |
Cash equivalents - financial instruments | 241,000,000 | 206,000,000 |
Marketable securities | | |
Marketable securities | 13,445,000,000 | 15,844,000,000 |
Derivative Financial Instrument Assets | | |
Derivative financial instruments assets | 1,102,000,000 | 517,000,000 |
Total assets at fair value | 14,788,000,000 | 16,567,000,000 |
Derivative financial instruments liabilities | | |
Derivative financial instruments liabilities | 1,260,000,000 | 710,000,000 |
Total liabilities at fair value | 1,260,000,000 | 710,000,000 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | US Treasury and Government [Member] | | |
Cash equivalents - financial instruments | | |
Cash equivalents - financial instruments | 11,000,000 | 64,000,000 |
Marketable securities | | |
Marketable securities | 3,290,000,000 | 5,789,000,000 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Foreign Government and Agencies [Member] | | |
Cash equivalents - financial instruments | | |
Cash equivalents - financial instruments | 220,000,000 | 122,000,000 |
Marketable securities | | |
Marketable securities | 6,911,000,000 | 7,004,000,000 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Corporate Debt [Domain] | | |
Cash equivalents - financial instruments | | |
Cash equivalents - financial instruments | 10,000,000 | 20,000,000 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Corporate Debt [Member] | | |
Marketable securities | | |
Marketable securities | 2,922,000,000 | 2,738,000,000 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Equities [Member] | | |
Marketable securities | | |
Marketable securities | 0 | 0 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Other marketable securities [Member] | | |
Marketable securities | | |
Marketable securities | 322,000,000 | 313,000,000 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | | |
Cash equivalents - financial instruments | | |
Cash equivalents - financial instruments | 0 | 0 |
Marketable securities | | |
Marketable securities | 0 | 0 |
Derivative Financial Instrument Assets | | |
Derivative financial instruments assets | 0 | 0 |
Total assets at fair value | 0 | 0 |
Derivative financial instruments liabilities | | |
Derivative financial instruments liabilities | 6,000,000 | 3,000,000 |
Total liabilities at fair value | 6,000,000 | 3,000,000 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | US Treasury and Government [Member] | | |
Cash equivalents - financial instruments | | |
Cash equivalents - financial instruments | 0 | 0 |
Marketable securities | | |
Marketable securities | 0 | 0 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Foreign Government and Agencies [Member] | | |
Cash equivalents - financial instruments | | |
Cash equivalents - financial instruments | 0 | 0 |
Marketable securities | | |
Marketable securities | 0 | 0 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Corporate Debt [Domain] | | |
Cash equivalents - financial instruments | | |
Cash equivalents - financial instruments | 0 | 0 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Corporate Debt [Member] | | |
Marketable securities | | |
Marketable securities | 0 | 0 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Equities [Member] | | |
Marketable securities | | |
Marketable securities | 0 | 0 |
Automotive [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Other marketable securities [Member] | | |
Marketable securities | | |
Marketable securities | 0 | 0 |
Financial Services [Member] | | |
Derivative Financial Instrument Assets | | |
Derivative financial instruments assets | 1,204,000,000 | 859,000,000 |
Derivative financial instruments liabilities | | |
Derivative financial instruments liabilities | 297,000,000 | 167,000,000 |
Financial Services [Member] | Fair Value, Measurements, Recurring [Member] | | |
Cash equivalents - financial instruments | | |
Cash equivalents - financial instruments | 400,000,000 | 351,000,000 |
Marketable securities | | |
Marketable securities | 6,264,000,000 | 3,258,000,000 |
Derivative Financial Instrument Assets | | |
Derivative financial instruments assets | 1,204,000,000 | 859,000,000 |
Total assets at fair value | 7,868,000,000 | 4,468,000,000 |
Derivative financial instruments liabilities | | |
Derivative financial instruments liabilities | 297,000,000 | 167,000,000 |
Total liabilities at fair value | 297,000,000 | 167,000,000 |
Financial Services [Member] | Fair Value, Measurements, Recurring [Member] | US Treasury and Government [Member] | | |
Marketable securities | | |
Marketable securities | 4,006,000,000 | 1,268,000,000 |
Financial Services [Member] | Fair Value, Measurements, Recurring [Member] | Foreign Government and Agencies [Member] | | |
Cash equivalents - financial instruments | | |
Cash equivalents - financial instruments | 320,000,000 | 341,000,000 |
Marketable securities | | |
Marketable securities | 521,000,000 | 405,000,000 |
Financial Services [Member] | Fair Value, Measurements, Recurring [Member] | Corporate Debt [Domain] | | |
Cash equivalents - financial instruments | | |
Cash equivalents - financial instruments | 80,000,000 | 10,000,000 |
Financial Services [Member] | Fair Value, Measurements, Recurring [Member] | Corporate Debt [Member] | | |
Marketable securities | | |
Marketable securities | 1,706,000,000 | 1,555,000,000 |
Financial Services [Member] | Fair Value, Measurements, Recurring [Member] | Other marketable securities [Member] | | |
Marketable securities | | |
Marketable securities | 31,000,000 | 30,000,000 |
Financial Services [Member] | Fair Value, Measurements, Recurring [Member] | Cash equivalents - financial instruments [Member] | | |
Input Hierarchy of Items Measured at Fair Value on a Recurring Basis - Footnote Narrative | | |
Par Value Assets Excluded From Fair Value By Input | 5,100,000,000 | 3,800,000,000 |
Financial Services [Member] | Fair Value, Measurements, Recurring [Member] | Cash [Member] | | |
Input Hierarchy of Items Measured at Fair Value on a Recurring Basis - Footnote Narrative | | |
Par Value Assets Excluded From Fair Value By Input | 1,800,000,000 | 2,000,000,000 |
Financial Services [Member] | Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | | |
Cash equivalents - financial instruments | | |
Cash equivalents - financial instruments | 0 | 0 |
Marketable securities | | |
Marketable securities | 1,151,000,000 | 17,000,000 |
Derivative Financial Instrument Assets | | |
Derivative financial instruments assets | 0 | 0 |
Total assets at fair value | 1,151,000,000 | 17,000,000 |
Derivative financial instruments liabilities | | |
Derivative financial instruments liabilities | 0 | 0 |
Total liabilities at fair value | 0 | 0 |
Financial Services [Member] | Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | US Treasury and Government [Member] | | |
Marketable securities | | |
Marketable securities | 1,151,000,000 | 17,000,000 |
Financial Services [Member] | Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Foreign Government and Agencies [Member] | | |
Cash equivalents - financial instruments | | |
Cash equivalents - financial instruments | 0 | 0 |
Marketable securities | | |
Marketable securities | 0 | 0 |
Financial Services [Member] | Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Corporate Debt [Domain] | | |
Cash equivalents - financial instruments | | |
Cash equivalents - financial instruments | 0 | 0 |
Financial Services [Member] | Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Corporate Debt [Member] | | |
Marketable securities | | |
Marketable securities | 0 | 0 |
Financial Services [Member] | Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Other marketable securities [Member] | | |
Marketable securities | | |
Marketable securities | 0 | 0 |
Financial Services [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | | |
Cash equivalents - financial instruments | | |
Cash equivalents - financial instruments | 400,000,000 | 351,000,000 |
Marketable securities | | |
Marketable securities | 5,113,000,000 | 3,241,000,000 |
Derivative Financial Instrument Assets | | |
Derivative financial instruments assets | 1,204,000,000 | 859,000,000 |
Total assets at fair value | 6,717,000,000 | 4,451,000,000 |
Derivative financial instruments liabilities | | |
Derivative financial instruments liabilities | 297,000,000 | 167,000,000 |
Total liabilities at fair value | 297,000,000 | 167,000,000 |
Financial Services [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | US Treasury and Government [Member] | | |
Marketable securities | | |
Marketable securities | 2,855,000,000 | 1,251,000,000 |
Financial Services [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Foreign Government and Agencies [Member] | | |
Cash equivalents - financial instruments | | |
Cash equivalents - financial instruments | 320,000,000 | 341,000,000 |
Marketable securities | | |
Marketable securities | 521,000,000 | 405,000,000 |
Financial Services [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Corporate Debt [Domain] | | |
Cash equivalents - financial instruments | | |
Cash equivalents - financial instruments | 80,000,000 | 10,000,000 |
Financial Services [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Corporate Debt [Member] | | |
Marketable securities | | |
Marketable securities | 1,706,000,000 | 1,555,000,000 |
Financial Services [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Other marketable securities [Member] | | |
Marketable securities | | |
Marketable securities | 31,000,000 | 30,000,000 |
Financial Services [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | | |
Cash equivalents - financial instruments | | |
Cash equivalents - financial instruments | 0 | 0 |
Marketable securities | | |
Marketable securities | 0 | 0 |
Derivative Financial Instrument Assets | | |
Derivative financial instruments assets | 0 | 0 |
Total assets at fair value | 0 | 0 |
Derivative financial instruments liabilities | | |
Derivative financial instruments liabilities | 0 | 0 |
Total liabilities at fair value | 0 | 0 |
Financial Services [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | US Treasury and Government [Member] | | |
Marketable securities | | |
Marketable securities | 0 | 0 |
Financial Services [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Foreign Government and Agencies [Member] | | |
Cash equivalents - financial instruments | | |
Cash equivalents - financial instruments | 0 | 0 |
Marketable securities | | |
Marketable securities | 0 | 0 |
Financial Services [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Corporate Debt [Domain] | | |
Cash equivalents - financial instruments | | |
Cash equivalents - financial instruments | 0 | 0 |
Financial Services [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Corporate Debt [Member] | | |
Marketable securities | | |
Marketable securities | 0 | 0 |
Financial Services [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Other marketable securities [Member] | | |
Marketable securities | | |
Marketable securities | $0 | $0 |