v2.4.0.8

Employee Benefit Plans | 3 Months Ended
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Mar. 31, 2014
Compensation and Retirement Disclosure [Abstract] |
Employee Benefit Plans | Employee Benefit Plans We sponsor two union pension plans for certain union employees and a pension plan primarily for salaried employees, a postretirement benefit plan for selected employees and a defined contribution plan. The following tables present our consolidated net periodic benefit costs related to the pension and postretirement benefit plans for the three months ended March 31, 2013 and 2014 (in thousands):
| Three Months Ended |  | Three Months Ended
| March 31, 2013 |  | March 31, 2014
| Pension Benefits |  | Other Post- Retirement Benefits |  | Pension Benefits |  | Other Post- Retirement Benefits
Components of net periodic benefit costs: |  |  |  |  |  |  |
Service cost | $ | 3,576 |  |  | $ | 77 |  |  | $ | 3,352 |  |  | $ | 67 |
Interest cost | 1,350 |  |  | 115 |  |  | 1,659 |  |  | 114 |
Expected return on plan assets | (1,470 | ) |  | — |  |  | (1,697 | ) |  | — |
Amortization of prior service cost (credit)(1) | 77 |  |  | (928 | ) |  | 33 |  |  | (928 | )
Amortization of actuarial loss(1) | 1,022 |  |  | 308 |  |  | 629 |  |  | 195 |
Net periodic benefit cost (credit) | $ | 4,555 |  |  | $ | (428 | ) |  | $ | 3,976 |  |  | $ | (552 | )
(1) These amounts are included in our Consolidated Statements of Comprehensive Income and Consolidated Statements of Cash Flows as changes in employee benefit plan assets and benefit obligations.

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- Definition The entire disclosure for pension and other postretirement benefits. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -URI http://asc.fasb.org/topic&trid=2235017 + Details
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