Derivatives and Hedging - Schedule of amounts of derivative gains (losses) recognized in the Consolidated Financial Statements (Details) - Cash Flow Hedging [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	$ 14	$ 15	$ 13	$ 7
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	3	2	(8)	(20)
Interest rate contracts [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	0	0	0	0
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	0	0	(1)	(1)
Foreign exchange contracts [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	14	15	13	7
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	3	2	(7)	(19)
Compensation and Benefits [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	1	5	6	16
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	1	0	1	(2)
Compensation and Benefits [Member] | Interest rate contracts [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	0	0	0	0
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	0	0	0	0
Compensation and Benefits [Member] | Foreign exchange contracts [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	1	5	6	16
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	1	0	1	(2)
Other General Expenses [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	3	0	1	0
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	(1)	0	(1)	0
Other General Expenses [Member] | Interest rate contracts [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	0	0	0	0
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	0	0	0	0
Other General Expenses [Member] | Foreign exchange contracts [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	3	0	1	0
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	(1)	0	(1)	0
Interest Expense [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	0	0	0	0
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	(2)	(3)	(5)	(6)
Interest Expense [Member] | Interest rate contracts [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	$ 0	0	0	0
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):		0	(1)	(1)
Interest Expense [Member] | Foreign exchange contracts [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	$ 0	0	0	0
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	(2)	(3)	(4)	(5)
Other Income [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	10	10	6	(9)
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	5	5	(3)	(12)
Other Income [Member] | Interest rate contracts [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	0	0	0	0
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	0	0	0	0
Other Income [Member] | Foreign exchange contracts [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	10	10	6	(9)
Gain (Loss) reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion):	$ 5	$ 5	$ (3)	$ (12)