Borrowings - Note Issuances (Details)	Jun. 01, 2016 USD ($)	Feb. 28, 2017 EUR (€)	Feb. 28, 2017 USD ($)
Total $6.0 billion debt issuance
Debt Instrument [Line Items]
Face amount			$ 6,000,000,000
Fair value of the notes			6,000,000,000
Carrying value of the notes			6,000,000,000
Net proceeds from notes payable	$ 6,000,000,000
Total issuance costs	$ 30,000,000
Percentage of principal amount of fixed rate notes can be redeemed	101.00%
Total $8.0 billion debt issuance
Debt Instrument [Line Items]
Face amount			8,000,000,000
Fair value of the notes			7,400,000,000
Carrying value of the notes			7,200,000,000
Total 700 million pounds debt issuance
Debt Instrument [Line Items]
Face amount | €		€ 700,000,000.0
Fair value of the notes			900,000,000
Carrying value of the notes			900,000,000
Total 750 million euros debt issuance
Debt Instrument [Line Items]
Face amount | €		€ 750,000,000.00
Fair value of the notes			800,000,000
Carrying value of the notes			800,000,000
Total $4.0 billion debt issuance
Debt Instrument [Line Items]
Face amount			4,000,000,000
Fair value of the notes			1,700,000,000
Carrying value of the notes			1,700,000,000
Total $1.0 billion debt issuance
Debt Instrument [Line Items]
Face amount			1,000,000,000
Fair value of the notes			300,000,000
Carrying value of the notes			$ 200,000,000