Derivative Financial Instruments - Schedule of Notional Amounts of Outstanding Derivative Positions (Details) € in Millions, £ in Millions, CAD in Millions, AUD in Millions, $ in Millions	Jun. 30, 2016 EUR (€)	Jun. 30, 2016 USD ($)	Jun. 30, 2016 CAD	Jun. 30, 2016 AUD	Jun. 30, 2016 GBP (£)	Jan. 31, 2016 USD ($)	Dec. 31, 2015 EUR (€)	Dec. 31, 2015 USD ($)	Dec. 31, 2015 CAD	Dec. 31, 2015 AUD	Dec. 31, 2015 GBP (£)
Derivatives, Fair Value [Line Items]
Derivative Assets		$ 154						$ 179
Derivative Liabilities		(22)						(56)
Derivative asset subject to master netting agreements		154						179
Derivative liability subject to master netting agreement		20						51
Net derivative asset		134						128
Derivatives designated as hedges of net investments in foreign operations
Derivatives, Fair Value [Line Items]
Derivative Assets		154						179
Derivative Liabilities		0						0
Derivatives designated as hedges of net investments in foreign operations | Foreign exchange contracts | AUD
Derivatives, Fair Value [Line Items]
Notional Value | AUD				AUD 260						AUD 260
Derivative Assets		60						65
Derivative Liabilities		0						0
Derivatives designated as hedges of net investments in foreign operations | Foreign exchange contracts | EUR
Derivatives, Fair Value [Line Items]
Notional Value | €	€ 0						€ 200
Derivative Assets		0						51
Derivative Liabilities		0						0
Maturity of foreign exchange contracts, net settlement value						$ 49
Derivatives designated as hedges of net investments in foreign operations | Foreign exchange contracts | GBP
Derivatives, Fair Value [Line Items]
Notional Value | £					£ 250						£ 250
Derivative Assets		75						39
Derivative Liabilities		0						0
Derivatives designated as hedges of net investments in foreign operations | Foreign exchange contracts | CAD
Derivatives, Fair Value [Line Items]
Notional Value | CAD			CAD 110						CAD 110
Derivative Assets		19						24
Derivative Liabilities		0						0
Derivatives not designated as hedging instruments | Interest rate contracts | USD
Derivatives, Fair Value [Line Items]
Notional Value		5,000						5,000
Derivative Assets		0						0
Derivative Liabilities		$ (22)						$ (56)