Derivative Instruments - Notional Amounts of Derivatives Outstanding (Details) - USD ($) $ in Millions |
Mar. 31, 2017 |
Mar. 31, 2016 |
|---|---|---|
| Derivatives, Fair Value [Line Items] | ||
| Notional amount | $ 7,109 | $ 6,593 |
| Foreign Exchange Contract | Designated as Hedging Instrument | Cash Flow Hedging | ||
| Derivatives, Fair Value [Line Items] | ||
| Notional amount | 1,502 | 1,200 |
| Foreign Exchange Contract | Designated as Hedging Instrument | Net Investment Hedging | ||
| Derivatives, Fair Value [Line Items] | ||
| Notional amount | 96 | 0 |
| Foreign Exchange Contract | Not Designated as Hedging Instrument | ||
| Derivatives, Fair Value [Line Items] | ||
| Notional amount | 3,111 | 2,993 |
| Interest Rate Contract | Designated as Hedging Instrument | Fair Value Hedging | ||
| Derivatives, Fair Value [Line Items] | ||
| Notional amount | $ 2,400 | $ 2,400 |