Debt - Narrative (Details)	9 Months Ended
	Sep. 30, 2016 USD ($)	Oct. 25, 2016 USD ($)	Sep. 30, 2016 EUR (€)	Jul. 21, 2016 USD ($)	May 31, 2016 USD ($)	May 31, 2016 EUR (€)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Debt Instrument [Line Items]
Debt instrument, face amount	$ 27,340,000,000							$ 19,100,000,000
Medium-term Notes [Member] | Euro Medium Term Note Due May 2020 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount | €						€ 500,000,000
Interest rate (percent)					1.168%	1.168%
Medium-term Notes [Member] | Euro Medium Term Note Due September 2023 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount | €			€ 750,000,000
Interest rate (percent)	0.955%		0.955%
Secured Debt [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 11,849,000,000
Secured Debt [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Increase in credit facilities during period	$ 3,100,000,000
Parent Company [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, face amount					$ 3,000,000,000		$ 2,750,000,000.00
Parent Company [Member] | Senior Notes [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Debt instrument, face amount		$ 1,750,000,000.00
Parent Company [Member] | Senior Notes [Member] | 4.2% Senior Notes Due March 2021 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount							$ 1,500,000,000.0
Interest rate (percent)							4.20%
Parent Company [Member] | Senior Notes [Member] | 5.25% Senior Notes Due March 2026 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount							$ 1,250,000,000.00
Interest rate (percent)							5.25%
Parent Company [Member] | Senior Notes [Member] | 2.40% Senior Notes Due May 2019 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount					$ 1,400,000,000.0
Interest rate (percent)					2.40%	2.40%
Parent Company [Member] | Senior Notes [Member] | 3.70% Senior Notes Due May 2023 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount					$ 1,200,000,000.0
Interest rate (percent)					3.70%	3.70%
Parent Company [Member] | Senior Notes [Member] | Floating Rate Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, face amount					$ 400,000,000
Parent Company [Member] | Senior Notes [Member] | 3.2% Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount				$ 2,000,000,000
Interest rate (percent)				3.20%
Parent Company [Member] | Senior Notes [Member] | 2.35% Senior Notes Due October 2019 [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Debt instrument, face amount		$ 750,000,000
Interest rate (percent)		2.35%
Parent Company [Member] | Senior Notes [Member] | 4.00% Senior Notes Due October 2026 [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Debt instrument, face amount		$ 750,000,000
Interest rate (percent)		4.00%
Parent Company [Member] | Senior Notes [Member] | Floating Rate Senior Notes Due October 2019 [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Debt instrument, face amount		$ 250,000,000