Debt - Senior Notes (Details) - USD ($) $ in Millions |
3 Months Ended | |||
|---|---|---|---|---|
Mar. 31, 2017 |
Mar. 31, 2016 |
Dec. 31, 2016 |
Jul. 31, 2014 |
|
| Interest Rate Swap | Designated as Hedging Instrument | Fair Value Hedging | ||||
| Debt Instrument [Line Items] | ||||
| Derivative liability | $ 2,400 | $ 2,400 | ||
| Senior Notes | ||||
| Debt Instrument [Line Items] | ||||
| Redemption price, percentage, in the event of change of control | 101.00% | |||
| Interest expense | 68 | $ 50 | ||
| Fair value of long-term debt | $ 9,000 | $ 8,900 | ||
| Senior Notes | 2.500% Senior notes due 2018 | ||||
| Debt Instrument [Line Items] | ||||
| Coupon rate, fixed rate notes | 2.50% | 2.50% | ||
| Senior Notes | 3.800% Senior notes due 2022 | ||||
| Debt Instrument [Line Items] | ||||
| Coupon rate, fixed rate notes | 3.80% | 3.80% | ||
| Senior Notes | 6.000% Senior notes due 2056 | ||||
| Debt Instrument [Line Items] | ||||
| Coupon rate, fixed rate notes | 6.00% | 6.00% | ||
| Redemption price, percentage | 100.00% | |||