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EMPLOYEE BENEFIT PLANS (Settlement distributions and expense) (Details) - USD ($) $ / shares in Units, $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2017 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Distributions and pension settlement expense |  |  |  |  |
Pension settlement expense, pre-tax |  | $ 4,156 | $ 3,229 | $ 3,202 |
Nonunion Defined Benefit Pension Plan |  |  |  |  |
Distributions and pension settlement expense |  |  |  |  |
Pension settlement distributions |  | 26,261 | 16,515 | 20,622 |
Pension settlement expense, pre-tax |  | $ 4,156 | $ 3,023 | $ 3,202 |
Pension settlement expense per diluted share, net of taxes |  | $ 0.10 | $ 0.07 | $ 0.07 |
Lump-sum distributions |  | $ 18,700 |  |  |
Premium paid to purchase nonparticipating annuity contract | $ 7,600 | 7,600 |  |  |
Supplemental Benefit Plan |  |  |  |  |
Distributions and pension settlement expense |  |  |  |  |
Pension settlement distributions |  | $ 989 | $ 246 | $ 1,941 |
Pension settlement expense, pre-tax |  |  | $ 206 |  |
Pension settlement expense per diluted share, net of taxes |  |  | $ 0.01 |  |
Period of delay for pension settlement distribution to key employees |  |  | 6 months |  | 6 months

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- Definition The amount of lump sum benefit distributions paid. + References No definition available. + Details
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- Definition The amount of net gain (loss), per diluted share, net of taxes, recognized in net periodic benefit cost as a result of an irrevocable action that relieves the employer (or the plan) of primary responsibility for a benefit obligation and eliminates significant risks related to the obligation and the assets used to effect the settlement. + References No definition available. + Details
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- Definition Amount of premium paid for nonparticipating annuity contract to settle vested benefit obligations of participants and beneficiaries receiving monthly benefits. + References No definition available. + Details
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- Definition Amount of gain (loss) recognized in net periodic benefit (cost) credit from irrevocable action relieving primary responsibility for benefit obligation and eliminating risk related to obligation and assets used to effect settlement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(7) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition Amount of payment, which decreases plan assets of defined benefit plan, for irrevocable action relieving primary responsibility for benefit obligation and eliminating risk for obligation and assets used to effect settlement. Transaction constituting settlement includes, but is not limited to, making lump-sum cash payment to participant in exchange for their rights to receive specified benefits and purchasing nonparticipating annuity contract. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(5)(ii) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(5)(iv)(01) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b)(8) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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