Derivatives and Hedging - Schedule of amounts of derivative gains (losses) recognized in the Consolidated Financial Statements (Details) (Cash Flow Hedging [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	$ (1)	$ (8)
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	(11)	(21)
Interest rate contracts [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	0	0
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	(1)	0
Foreign exchange contracts [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	(1)	(8)
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	(10)	(21)
Compensation and Benefits [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	5	11
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	0	(3)
Compensation and Benefits [Member] | Interest rate contracts [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	0	0
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	0	0
Compensation and Benefits [Member] | Foreign exchange contracts [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	5	11
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	0	(3)
Other General Expenses [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	(2)	0
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	0	0
Other General Expenses [Member] | Interest rate contracts [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	0	0
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	0	0
Other General Expenses [Member] | Foreign exchange contracts [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	(2)	0
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	0	0
Interest Expense [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	0	0
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	(3)	0
Interest Expense [Member] | Interest rate contracts [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	0	0
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	(1)	0
Interest Expense [Member] | Foreign exchange contracts [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	0	0
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	(2)	0
Other Income [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	(4)	(19)
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	(8)	(18)
Other Income [Member] | Interest rate contracts [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	0	0
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	0	0
Other Income [Member] | Foreign exchange contracts [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	(4)	(19)
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	$ (8)	$ (18)