Fair Value Measurements - Input Hierarchy of Items Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Automotive [Member]
Assets [Abstract]
Derivative financial instruments assets	$ 521	$ 517
Derivative financial instruments liabilities
Derivative financial instruments liabilities	992	713
Financial Services [Member]
Assets [Abstract]
Derivative financial instruments assets	823	859
Derivative financial instruments liabilities
Derivative financial instruments liabilities	378	167
Fair Value, Measurements, Recurring [Member] | Automotive [Member]
Assets [Abstract]
Cash equivalents - financial instruments	267	206
Marketable securities	14,599	17,135
Derivative financial instruments assets	521	517
Total assets at fair value	15,387	17,858
Derivative financial instruments liabilities
Derivative financial instruments liabilities	992	713
Total liabilities at fair value	992	713
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | Cash equivalents - financial instruments [Member]
Input Hierarchy of Items Measured at Fair Value on Recurring Basis [Abstract]
Par Value Assets Excluded From Fair Value By Input	4,600	3,300
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | Cash [Member]
Input Hierarchy of Items Measured at Fair Value on Recurring Basis [Abstract]
Par Value Assets Excluded From Fair Value By Input	1,200	1,100
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | US Treasury and Government [Member]
Assets [Abstract]
Cash equivalents - financial instruments	8	64
Marketable securities	4,552	6,758
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | Foreign Government and Agencies [Member]
Assets [Abstract]
Cash equivalents - financial instruments	249	122
Marketable securities	6,068	7,004
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | Corporate Debt [Domain]
Assets [Abstract]
Cash equivalents - financial instruments	10	20
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | Corporate Debt [Member]
Assets [Abstract]
Marketable securities	3,617	2,738
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | Equities [Member]
Assets [Abstract]
Marketable securities	15	322
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | Other marketable securities [Member]
Assets [Abstract]
Marketable securities	347	313
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | Level 1 [Member]
Assets [Abstract]
Cash equivalents - financial instruments	0	0
Marketable securities	861	1,291
Derivative financial instruments assets	0	0
Total assets at fair value	861	1,291
Derivative financial instruments liabilities
Derivative financial instruments liabilities	0	0
Total liabilities at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | Level 1 [Member] | US Treasury and Government [Member]
Assets [Abstract]
Cash equivalents - financial instruments	0	0
Marketable securities	846	969
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | Level 1 [Member] | Foreign Government and Agencies [Member]
Assets [Abstract]
Cash equivalents - financial instruments	0	0
Marketable securities	0	0
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | Level 1 [Member] | Corporate Debt [Domain]
Assets [Abstract]
Cash equivalents - financial instruments	0	0
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | Level 1 [Member] | Corporate Debt [Member]
Assets [Abstract]
Marketable securities	0	0
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | Level 1 [Member] | Equities [Member]
Assets [Abstract]
Marketable securities	15	322
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | Level 1 [Member] | Other marketable securities [Member]
Assets [Abstract]
Marketable securities	0	0
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | Level 2 [Member]
Assets [Abstract]
Cash equivalents - financial instruments	267	206
Marketable securities	13,738	15,844
Derivative financial instruments assets	521	517
Total assets at fair value	14,526	16,567
Derivative financial instruments liabilities
Derivative financial instruments liabilities	991	710
Total liabilities at fair value	991	710
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | Level 2 [Member] | US Treasury and Government [Member]
Assets [Abstract]
Cash equivalents - financial instruments	8	64
Marketable securities	3,706	5,789
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | Level 2 [Member] | Foreign Government and Agencies [Member]
Assets [Abstract]
Cash equivalents - financial instruments	249	122
Marketable securities	6,068	7,004
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | Level 2 [Member] | Corporate Debt [Domain]
Assets [Abstract]
Cash equivalents - financial instruments	10	20
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | Level 2 [Member] | Corporate Debt [Member]
Assets [Abstract]
Marketable securities	3,617	2,738
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | Level 2 [Member] | Equities [Member]
Assets [Abstract]
Marketable securities	0	0
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | Level 2 [Member] | Other marketable securities [Member]
Assets [Abstract]
Marketable securities	347	313
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | Level 3 [Member]
Assets [Abstract]
Cash equivalents - financial instruments	0	0
Marketable securities	0	0
Derivative financial instruments assets	0	0
Total assets at fair value	0	0
Derivative financial instruments liabilities
Derivative financial instruments liabilities	1	3
Total liabilities at fair value	1	3
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | Level 3 [Member] | US Treasury and Government [Member]
Assets [Abstract]
Cash equivalents - financial instruments	0	0
Marketable securities	0	0
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | Level 3 [Member] | Foreign Government and Agencies [Member]
Assets [Abstract]
Cash equivalents - financial instruments	0	0
Marketable securities	0	0
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | Level 3 [Member] | Corporate Debt [Domain]
Assets [Abstract]
Cash equivalents - financial instruments	0	0
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | Level 3 [Member] | Corporate Debt [Member]
Assets [Abstract]
Marketable securities	0	0
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | Level 3 [Member] | Equities [Member]
Assets [Abstract]
Marketable securities	0	0
Fair Value, Measurements, Recurring [Member] | Automotive [Member] | Level 3 [Member] | Other marketable securities [Member]
Assets [Abstract]
Marketable securities	0	0
Fair Value, Measurements, Recurring [Member] | Financial Services [Member]
Assets [Abstract]
Cash equivalents - financial instruments	469	351
Marketable securities	3,806	3,258
Derivative financial instruments assets	823	859
Total assets at fair value	5,098	4,468
Derivative financial instruments liabilities
Derivative financial instruments liabilities	378	167
Total liabilities at fair value	378	167
Fair Value, Measurements, Recurring [Member] | Financial Services [Member] | Cash equivalents - financial instruments [Member]
Input Hierarchy of Items Measured at Fair Value on Recurring Basis [Abstract]
Par Value Assets Excluded From Fair Value By Input	3,900	3,800
Fair Value, Measurements, Recurring [Member] | Financial Services [Member] | Cash [Member]
Input Hierarchy of Items Measured at Fair Value on Recurring Basis [Abstract]
Par Value Assets Excluded From Fair Value By Input	2,400	2,000
Fair Value, Measurements, Recurring [Member] | Financial Services [Member] | US Treasury and Government [Member]
Assets [Abstract]
Marketable securities	1,369	1,268
Fair Value, Measurements, Recurring [Member] | Financial Services [Member] | Foreign Government and Agencies [Member]
Assets [Abstract]
Cash equivalents - financial instruments	419	341
Marketable securities	630	405
Fair Value, Measurements, Recurring [Member] | Financial Services [Member] | Corporate Debt [Domain]
Assets [Abstract]
Cash equivalents - financial instruments	50	10
Fair Value, Measurements, Recurring [Member] | Financial Services [Member] | Corporate Debt [Member]
Assets [Abstract]
Marketable securities	1,780	1,555
Fair Value, Measurements, Recurring [Member] | Financial Services [Member] | Other marketable securities [Member]
Assets [Abstract]
Marketable securities	27	30
Fair Value, Measurements, Recurring [Member] | Financial Services [Member] | Level 1 [Member]
Assets [Abstract]
Cash equivalents - financial instruments	0	0
Marketable securities	669	17
Derivative financial instruments assets	0	0
Total assets at fair value	669	17
Derivative financial instruments liabilities
Derivative financial instruments liabilities	0	0
Total liabilities at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Financial Services [Member] | Level 1 [Member] | US Treasury and Government [Member]
Assets [Abstract]
Marketable securities	669	17
Fair Value, Measurements, Recurring [Member] | Financial Services [Member] | Level 1 [Member] | Foreign Government and Agencies [Member]
Assets [Abstract]
Cash equivalents - financial instruments	0	0
Marketable securities	0	0
Fair Value, Measurements, Recurring [Member] | Financial Services [Member] | Level 1 [Member] | Corporate Debt [Domain]
Assets [Abstract]
Cash equivalents - financial instruments	0	0
Fair Value, Measurements, Recurring [Member] | Financial Services [Member] | Level 1 [Member] | Corporate Debt [Member]
Assets [Abstract]
Marketable securities	0	0
Fair Value, Measurements, Recurring [Member] | Financial Services [Member] | Level 1 [Member] | Other marketable securities [Member]
Assets [Abstract]
Marketable securities	0	0
Fair Value, Measurements, Recurring [Member] | Financial Services [Member] | Level 2 [Member]
Assets [Abstract]
Cash equivalents - financial instruments	469	351
Marketable securities	3,137	3,241
Derivative financial instruments assets	823	859
Total assets at fair value	4,429	4,451
Derivative financial instruments liabilities
Derivative financial instruments liabilities	378	167
Total liabilities at fair value	378	167
Fair Value, Measurements, Recurring [Member] | Financial Services [Member] | Level 2 [Member] | US Treasury and Government [Member]
Assets [Abstract]
Marketable securities	700	1,251
Fair Value, Measurements, Recurring [Member] | Financial Services [Member] | Level 2 [Member] | Foreign Government and Agencies [Member]
Assets [Abstract]
Cash equivalents - financial instruments	419	341
Marketable securities	630	405
Fair Value, Measurements, Recurring [Member] | Financial Services [Member] | Level 2 [Member] | Corporate Debt [Domain]
Assets [Abstract]
Cash equivalents - financial instruments	50	10
Fair Value, Measurements, Recurring [Member] | Financial Services [Member] | Level 2 [Member] | Corporate Debt [Member]
Assets [Abstract]
Marketable securities	1,780	1,555
Fair Value, Measurements, Recurring [Member] | Financial Services [Member] | Level 2 [Member] | Other marketable securities [Member]
Assets [Abstract]
Marketable securities	27	30
Fair Value, Measurements, Recurring [Member] | Financial Services [Member] | Level 3 [Member]
Assets [Abstract]
Cash equivalents - financial instruments	0	0
Marketable securities	0	0
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
Fair Value, Measurements, Recurring [Member] | Financial Services [Member] | Level 3 [Member] | US Treasury and Government [Member]
Assets [Abstract]
Marketable securities	0	0
Fair Value, Measurements, Recurring [Member] | Financial Services [Member] | Level 3 [Member] | Foreign Government and Agencies [Member]
Assets [Abstract]
Cash equivalents - financial instruments	0	0
Marketable securities	0	0
Fair Value, Measurements, Recurring [Member] | Financial Services [Member] | Level 3 [Member] | Corporate Debt [Domain]
Assets [Abstract]
Cash equivalents - financial instruments	0	0
Fair Value, Measurements, Recurring [Member] | Financial Services [Member] | Level 3 [Member] | Corporate Debt [Member]
Assets [Abstract]
Marketable securities	0	0
Fair Value, Measurements, Recurring [Member] | Financial Services [Member] | Level 3 [Member] | Other marketable securities [Member]
Assets [Abstract]
Marketable securities	$ 0	$ 0