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Benefit Plans Components of Benefit Plans (Details) (USD $) | 12 Months Ended
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Dec. 31, 2014 | Dec. 31, 2013 Number_of_defined_benefit_plan_investment_funds | Sep. 30, 2013 Number_of_qualified_defined_benefit_pension_plans Number_of_defined_benefit_plan_structures plans Number_of_qualified_defined_contribution_plans Years | Dec. 31, 2012 | Sep. 30, 2012 | Dec. 31, 2011 | Sep. 30, 2011 | Dec. 31, 2010
Defined Benefit Plan Disclosure |  |  |  |  |  |  |  |
Number of defined benefit plans |  |  | 1 |  |  |  |  |
Number of definied contribution plans |  |  | 1 |  |  |  |  |
Number of unfunded post-retirement health care plans |  |  | 2 |  |  |  |  |
Number of benefit plan structures |  |  | 2 |  |  |  |  |
Number of consecutive highest base pay years |  |  | 3 |  |  |  |  |
Percentage of straight-time earnings for cash balance benefit credit |  |  | 6.00% |  |  |  |  |
Percentage added to consumer price index for interest credit of cash balance benefit |  |  | 3.00% |  |  |  |  |
Minimum interest credit percentage for cash balance benefit |  |  | 6.00% |  |  |  |  |
Maximum interest credit percentage for cash balance benefit |  |  | 10.00% |  |  |  |  |
Rate of cash balance benefit credit for calendar year |  | 6.00% |  |  | 6.00% |  |  |
Number of defined benefit plan investment funds |  | 2 |  |  |  |  |  |
Fixed and variable fund annual maximum contribution |  |  |  |  | $ 10,000 |  |  |
Fixed fund balance interest credits after January 1, 2010 |  |  | 6.00% |  |  |  |  |
Fixed fund balance credit percentage subtracted from the actuarial rate of return after January 1, 2010 |  |  | 0.50% |  |  |  |  |
Fixed fund interest credit rate |  |  | 6.00% | 6.00% |  |  |  |
Fixed fund interest credit amount |  |  | 36,000,000 |  | 38,000,000 |  |  |
Defined contribution plan contribution amount |  |  | 34,000,000 |  | 34,000,000 |  | 31,000,000 |
Market-related value phase-in period number of years |  |  | 3 |  |  |  |  |
Number of years during which cost of living adjustment changed | 4 years |  |  |  |  |  |  |
Cost of Living Adjustment Cap |  | 2.30% |  | 0.00% |  | 1.15% |  | 0.00%
Cost of living adjustment cap for calendar year 2014 and forward | 5.00% |  |  |  |  |  |  |
Retirement age of eligibility for cost of living adjustment after January 1, 2010 |  |  |  |  |  |  |  | 60
Original benefit structure |  |  |  |  |  |  |  |
Defined Benefit Plan Disclosure |  |  |  |  |  |  |  |
Defined contribution plan employer matching contribution rate |  |  | 0.25 |  |  |  |  |
Defined contribution plan, maximum annual contribution per employee, percent |  |  | 1.50% |  |  |  |  |
Cash Balance Benefit Structure |  |  |  |  |  |  |  |
Defined Benefit Plan Disclosure |  |  |  |  |  |  |  |
Defined contribution plan employer matching contribution rate |  |  | $ 0.75 |  |  |  |  |
Defined contribution plan, maximum annual contribution per employee, percent |  |  | 4.50% |  |  |  |  |

X
- Definition The percentage cap for of the cost of living adjustment. + References No definition available. + Details
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- Definition The percentage cap for of the cost of living adjustment for calendar year 2014 and forward. + References No definition available. + Details
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- Definition The amount per dollar that an employer matches employee contributions to a defined contribution plan. + References No definition available. + Details
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- Definition The maximum annual contribution that employees can make to the fixed and variable fund benefit. The fixed fund benefit is a benefit that earns a specified rate of interest on contributions made by employees. The variable fund is a benefit that invests employee contributions in the Spartan U.S. Equity Index Fund-Fidelity Advantage Class (Spartan). + References No definition available. + Details
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- Definition The interest rate subtracted from the actuarial return and compared to six percent to credit balances in the fixed fund benefit after January 1, 2010. The lesser of the two interest rates is used to credit the fixed fund balances. The fixed fund benefit is a benefit that earns a specified rate of interest on employee contributions. + References No definition available. + Details
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- Definition The interest rate compared to the actuarial return less 0.5 percent to credit balances in a fixed fund benefit after January 1, 2010. The lesser of the two interest rates is used to credit the fixed fund balances. The fixed fund benefit is a benefit that earns a specified rate of interest on employee contributions. + References No definition available. + Details
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- Definition The amount of interest credited to balances in the fixed fund benefit. The fixed fund benefit is a benefit that earns a specified rate of interest on employee contributions. + References No definition available. + Details
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- Definition The interest rate used to credit balances in the fixed fund benefit. The fixed fund benefit is a benefit that earns a specified rate of interest on employee contributions. + References No definition available. + Details
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- Definition The number of years for the phase-in period in which the impact of asset performance on pension expense is phased-in through a market-related value of asset calculation. + References No definition available. + Details
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- Definition The maximum interest credit percentage for accounts of members of the Cash Balance Benefit. + References No definition available. + Details
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- Definition The minimum interest credit percentage for accounts of memebers of the Cash Balance Benefit. + References No definition available. + Details
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- Definition Number of defined benefit plan pension structures + References No definition available. + Details
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- Definition The number of consecutive highest base pay years used to calculate the member's average monthly salary for those members participating in the Original Benefit Structure. + References No definition available. + Details
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- Definition The number of defined benefit plan investment funds. + References No definition available. + Details
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- Definition The number of qualified defined benefit pension plans. + References No definition available. + Details
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- Definition The number of qualified defined contribution pension plans. + References No definition available. + Details
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- Definition The number of unfunded post-retirement health care plans that provide for non-vested contributions toward the cost of certain retirees' medical coverage. + References No definition available. + Details
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- Definition Number of years during which cost of living adjustment changed. + References No definition available. + Details
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- Definition The percentage added to the consumer price index for the interest credit to members' accounts of the Cash Balance Benefit + References No definition available. + Details
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- Definition The percentage of straight-time earnings that is used to credit the accounts of Cash Balance Benefit members. + References No definition available. + Details
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- Definition The percentage of Cash Balance Benefit credit for specific calendar years. + References No definition available. + Details
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- Definition Retirement age of eligibility for cost of living adjustment after January 1, 2010. + References No definition available. + Details
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- Details
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- Definition The amount of the cost recognized during the period for defined contribution plans. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6414718&loc=d3e28014-114942 + Details
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- Definition Maximum percentage of employee gross pay the employee may contribute to a defined contribution plan. + References No definition available. + Details
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