v2.4.0.8

Investments (Tables) | 6 Months Ended
--- | ---
Jun. 30, 2014
Investments [Abstract] |
Investment Holdings, Schedule of Investments [Table Text Block] | A summary of our investments, including our approximate ownership percentage and carrying value as of June 30, 2014 and December 31, 2013, is presented below.
|  |  |  | Approximate Ownership % |  | Carrying Value
|  | Accounting Method |  | June 30, 2014 |  | December 31, 2013 |  | June 30, 2014 |  | December 31, 2013
|  |  |  |  |  |  |  | ($ in millions)
FTS International, Inc. |  | Equity |  | 30% |  | 30% |  | $ | 119 |  |  | $ | 138 |
Sundrop Fuels, Inc. |  | Equity |  | 56% |  | 56% |  | 133 |  |  | 135 |
Chaparral Energy, Inc. |  | Equity |  | —% |  | 20% |  | — |  |  | 143 |
Other |  | — |  | —% |  | —% |  | 12 |  |  | 61 |
Total investments |  | $ | 264 |  |  | $ | 477 |

X
- Definition Tabular disclosure of data and information required in the supplementary schedule applicable to management investment companies listing holdings of unaffiliated investments. + References No definition available. + Details
Name: | us-gaap_InvestmentHoldingsScheduleOfInvestmentsTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_InvestmentsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration