Assets And Liabilities Measured At Fair Value Realized Unrealized Gain Loss (Details) - USD ($) $ in Millions |
3 Months Ended | |
|---|---|---|
Mar. 31, 2016 |
Mar. 31, 2015 |
|
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ||
| Realized and unrealized gains (losses) on financial instruments, net | $ (7) | $ (4) |
| Fair Value Option Securities | ||
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ||
| Realized and unrealized gains (losses) on financial instruments, net | 136 | (17) |
| Exchangeable Senior Debentures | ||
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ||
| Realized and unrealized gains (losses) on financial instruments, net | (142) | $ 13 |
| Other Financial Instruments | ||
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ||
| Realized and unrealized gains (losses) on financial instruments, net | $ (1) | |