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Employee Benefits and Other Expenses Textuals (Details) (USD $)
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12 Months Ended | ||
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Dec. 31, 2012
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Dec. 31, 2011
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Dec. 31, 2010
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| Employee Benefits and Other Expenses (Textual) [Abstract] | |||
| Employer contribution | $ 0 | ||
| Net actuarial loss to be amortized from accumulated other comprehensive income into net periodic benefit cost in the next twelve months | 182,000,000 | ||
| Net prior service credit to be amortized from accumulated other comprehensive income into net periodic benefit cost in the next twelve months | 2,000,000 | ||
| Defined Contribution Plan, terms | Under the 401(k) Plan, after one month of service, eligible employees may contribute up to 50% of their certified compensation, although there may be a lower limit for certain highly compensated employees in order to maintain the qualified status of the 401(k) Plan. Eligible employees who complete one year of service are eligible for company matching contributions, which are generally dollar for dollar up to 6% of an employee's eligible certified compensation. Effective January 1, 2010, previous and future matching contributions are 100% vested for active participants. | ||
| Employer contribution in shares of common stock to plan accounts of employees, percentage of certified compensation | 2.00% | ||
| Employer contribution in shares of common stock to plan accounts of employees, dollar amount | 318,000,000 | 311,000,000 | 316,000,000 |
| Defined contribution retirement plan expense | 1,143,000,000 | 1,104,000,000 | 1,092,000,000 |
| Assumed Health Care Cost Trend Rates Textuals [Abstract] | |||
| Increase in benefit obligation due to increasing assumed health care trend by one percentage point | 58,000,000 | ||
| Increase in total interest cost and service cost components of the net periodic benefit cost due to increasing assumed health care trend by one percentage point | 3,000,000 | ||
| Decrease in benefit obligation due to decreasing assumed health care trend by one percentage point | 52,000,000 | ||
| Decrease in total interest cost and service cost components of the net periodic benefit cost due to decreasing assumed health care trend by one percentage point | $ 2,000,000 | ||
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Long duration fixed income [Member]
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| Investment Strategy and Asset Allocation [Abstract] | |||
| Benefit Plan Investment Diversification | This category includes a diversified mix of assets which are being managed in accordance with a duration target of approximately 10 years and an emphasis on corporate credit bonds combined with investments in U.S. Treasury securities and other U.S. agency and non-agency bonds. | ||
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Intermediate (core) fixed income [Member]
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| Investment Strategy and Asset Allocation [Abstract] | |||
| Benefit Plan Investment Diversification | This category includes assets that are primarily intermediate duration, investment grade bonds held in investment strategies benchmarked to the Barclays Capital U.S. Aggregate Bond Index. Includes U.S. Treasury securities, agency and non-agency asset-backed bonds and corporate bonds. | ||
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Domestic large-cap stocks [Member]
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| Investment Strategy and Asset Allocation [Abstract] | |||
| Benefit Plan Investment Diversification | Assets in this category are currently diversified across eight unique investment strategies. For December 31, 2012 and 2011, respectively, approximately 24% and 34% of the assets within this category are passively managed to popular mainstream market indexes including the Standard & Poor's 500 Index; excluding the allocation to the S&P 500 Index strategy, no single investment manager represents more than 2.5% of total plan assets. | ||
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Domestic small-cap stocks [Member]
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| Investment Strategy and Asset Allocation [Abstract] | |||
| Benefit Plan Investment Diversification | This category consists of a highly diversified combination of four distinct investment management strategies with no single strategy representing more than 2% of total plan assets. Allocations in this category are primarily spread across actively managed approaches with distinct value and growth emphasized approaches in fairly equal proportions. | ||
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International stocks [Member]
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| Investment Strategy and Asset Allocation [Abstract] | |||
| Benefit Plan Investment Diversification | This category includes assets diversified across six unique investment strategies providing exposure to companies based primarily in developed market, non-U.S. countries with no single strategy representing more than 2.5% of total plan assets. | ||
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Real estate/timber [Member]
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| Investment Strategy and Asset Allocation [Abstract] | |||
| Benefit Plan Investment Diversification | This category primarily includes investments in private and public real estate, as well as timber specific limited partnerships; real estate holdings are diversified by geographic location and sector (e.g., retail, office, apartments). | ||
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Multi-strategy hedge funds [Member]
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| Investment Strategy and Asset Allocation [Abstract] | |||
| Benefit Plan Investment Diversification | This category consists of several investment strategies diversified across more than 30 hedge fund managers. Single manager allocation exposure is limited to 0.15% (15 basis points) of total plan assets | ||
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Real Estate, Venture Capital, Private Equity and Other Investments [Member] [Member]
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| Investment Strategy and Asset Allocation [Abstract] | |||
| Target asset allocation | 10.00% | ||
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Postretirement Projected Benefit Obligation [Member]
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| Assumed Health Care Cost Trend Rates Textuals [Abstract] | |||
| Defined Benefit Plan, Description of Direction and Pattern of Change for Assumed Health Care Cost Trend Rate | These rates are assumed to trend down 0.25% per year | ||
| Ultimate health care cost trend rate | 5.00% | ||
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Postretirement Projected Benefit Obligation [Member] | Minimum [Member]
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| Assumed Health Care Cost Trend Rates Textuals [Abstract] | |||
| Health care cost trend rate assumed for next fiscal year | 7.00% | ||
| Year that rate reaches ultimate health care cost trend rate | 2020 | ||
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Postretirement Projected Benefit Obligation [Member] | Maximum [Member]
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| Assumed Health Care Cost Trend Rates Textuals [Abstract] | |||
| Health care cost trend rate assumed for next fiscal year | 8.75% | ||
| Year that rate reaches ultimate health care cost trend rate | 2028 | ||
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Periodic Benefit Cost [Member]
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| Assumed Health Care Cost Trend Rates Textuals [Abstract] | |||
| Health care cost trend rate assumed for next fiscal year | 7.75% | ||
| Defined Benefit Plan, Description of Direction and Pattern of Change for Assumed Health Care Cost Trend Rate | These rates were assumed to decrease 0.25% per year | ||
| Ultimate health care cost trend rate | 5.00% | ||
| Year that rate reaches ultimate health care cost trend rate | 2023 | ||
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Cash Balance Plan [Member] | Equity Securities [Member]
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| Investment Strategy and Asset Allocation [Abstract] | |||
| Asset allocation, minimum of target mix range | 35.00% | ||
| Asset allocation, maximum of target mix range | 55.00% | ||
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Cash Balance Plan [Member] | Fixed Income [Member]
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| Investment Strategy and Asset Allocation [Abstract] | |||
| Asset allocation, minimum of target mix range | 35.00% | ||
| Asset allocation, maximum of target mix range | 55.00% | ||
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401(h) trust [Member] | Equity Securities [Member]
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| Investment Strategy and Asset Allocation [Abstract] | |||
| Asset allocation, minimum of target mix range | 40.00% | ||
| Asset allocation, maximum of target mix range | 60.00% | ||
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401(h) trust [Member] | Fixed Income [Member]
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| Investment Strategy and Asset Allocation [Abstract] | |||
| Asset allocation, minimum of target mix range | 40.00% | ||
| Asset allocation, maximum of target mix range | 60.00% | ||
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VEBA [Member] | Equity Securities [Member]
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| Investment Strategy and Asset Allocation [Abstract] | |||
| Asset allocation, minimum of target mix range | 20.00% | ||
| Asset allocation, maximum of target mix range | 40.00% | ||
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VEBA [Member] | Fixed Income [Member]
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| Investment Strategy and Asset Allocation [Abstract] | |||
| Asset allocation, minimum of target mix range | 60.00% | ||
| Asset allocation, maximum of target mix range | 80.00% | ||
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Pension Benefits [Member]
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| Employee Benefits and Other Expenses (Textual) [Abstract] | |||
| Discount rate, benefit obligation | 4.00% | 5.00% | |
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Other benefits [Member]
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| Employee Benefits and Other Expenses (Textual) [Abstract] | |||
| Discount rate, benefit obligation | 3.75% | 4.75% | |