XML 29 R18.htm IDEA: XBRL DOCUMENT
v3.10.0.1

EMPLOYEE BENEFIT PLANS EMPLOYEE BENEFIT PLANS (Notes) | 6 Months Ended
--- | ---
Jun. 30, 2018
Defined Benefit Plan [Abstract] |
EMPLOYEE BENEFIT PLANS | EMPLOYEE BENEFIT PLANS The following tables set forth the components of net periodic benefit cost for our pension and postretirement benefit plans for the periods indicated:
| Pension Benefits
| Three Months Ended |  | Six Months Ended
| June 30, |  | June 30,
| 2018 |  | 2017 |  | 2018 |  | 2017
| (Thousands of dollars)
Components of net periodic benefit cost |  |  |  |  |  |  |
Service cost | $ | 1,832 |  |  | $ | 1,722 |  |  | $ | 3,664 |  |  | $ | 3,444 |
Interest cost | 4,408 |  |  | 4,655 |  |  | 8,816 |  |  | 9,310 |
Expected return on plan assets | (5,969 | ) |  | (5,336 | ) |  | (11,938 | ) |  | (10,672 | )
Amortization of net loss | 4,258 |  |  | 3,392 |  |  | 8,516 |  |  | 6,784 |
Net periodic benefit cost | $ | 4,529 |  |  | $ | 4,433 |  |  | $ | 9,058 |  |  | $ | 8,866 |
| Postretirement Benefits
| Three Months Ended |  | Six Months Ended
| June 30, |  | June 30,
| 2018 |  | 2017 |  | 2018 |  | 2017
| (Thousands of dollars)
Components of net periodic benefit cost |  |  |  |  |  |  |
Service cost | $ | 211 |  |  | $ | 165 |  |  | $ | 422 |  |  | $ | 330 |
Interest cost | 527 |  |  | 565 |  |  | 1,054 |  |  | 1,130 |
Expected return on plan assets | (672 | ) |  | (564 | ) |  | (1,344 | ) |  | (1,128 | )
Amortization of prior service credit | (415 | ) |  | (415 | ) |  | (830 | ) |  | (830 | )
Amortization of net loss | 334 |  |  | 420 |  |  | 668 |  |  | 840 |
Net periodic benefit cost (income) | $ | (15 | ) |  | $ | 171 |  |  | $ | (30 | ) |  | $ | 342 |

X
- References No definition available. + Details
Name: | us-gaap_DefinedBenefitPensionPlansAndDefinedBenefitPostretirementPlansDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- 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
Name: | us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration