Notional Amounts of Outstanding Derivative Instruments (Detail) - USD ($) $ in Millions |
Mar. 31, 2017 |
Dec. 31, 2016 |
|---|---|---|
| Interest Rate Swaps | ||
| Derivative [Line Items] | ||
| Notional amount | $ 16,595 | $ 13,099 |
| Cross Currency Swaps | ||
| Derivative [Line Items] | ||
| Notional amount | 12,890 | 12,890 |
| Interest Rate Caps | ||
| Derivative [Line Items] | ||
| Notional amount | $ 2,540 | $ 2,540 |