Derivatives and Hedging - Schedule of amounts of derivative gains (losses) recognized in the Consolidated Financial Statements (Details) - Designated as Hedging Instrument [Member] - Cash Flow Hedging [Member] - Foreign Exchange Contract [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	$ (9)	$ (2)	$ (4)
Gain (loss) reclassified from accumulated other comprehensive loss into income (effective portion)	(17)	(14)	(10)
Compensation and Benefits [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	4	11	(17)
Gain (loss) reclassified from accumulated other comprehensive loss into income (effective portion)	4	(5)	(12)
Other General Expenses [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	(3)	(3)	0
Gain (loss) reclassified from accumulated other comprehensive loss into income (effective portion)	(1)	3	(9)
Interest Expense [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	0	0	0
Gain (loss) reclassified from accumulated other comprehensive loss into income (effective portion)	(9)	(10)	(3)
Other Income [Member]
Derivative [Line Items]
Gain (loss) recognized in accumulated other comprehensive income	(10)	(10)	13
Gain (loss) reclassified from accumulated other comprehensive loss into income (effective portion)	$ (11)	$ (2)	$ 14