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PENSION AND OTHER POSTRETIREMENT BENEFITS - FAIR VALUE OF PLAN ASSETS (Details)
$ in Thousands
 12 Months Ended
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Dec. 31, 2016
USD ($)
category
Pension Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets $ 184,824 $ 180,523 $ 189,542
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 184,824 180,523  
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year $ 189,542 184,824  
Pension Benefits | Minimum      
Defined Benefit Plan Disclosure [Line Items]      
Fund Valuations Lag Period 90 days    
Pension Benefits | Maximum      
Defined Benefit Plan Disclosure [Line Items]      
Fund Valuations Lag Period 120 days    
Pension Benefits | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets $ 19,702 19,702 23,674
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 19,702    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 23,674 19,702  
Pension Benefits | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 138,176 138,176 141,859
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 138,176    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 141,859 138,176  
Pension Benefits | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 26,946 26,335 24,009
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 26,946 26,335  
Actual return on plan assets:      
Relating to assets still held at the reporting date 1,014 459  
Relating to assets sold during the period 259 454  
Purchases, Sales and Settlements (4,210) (302)  
Fair Value of Plan Assets at End of Year 24,009 26,946  
Pension Benefits | Common/Collective Trust Funds - U.S.      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 52,058 52,058 51,902
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 52,058    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 51,902 52,058  
Pension Benefits | Common/Collective Trust Funds - U.S. | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Common/Collective Trust Funds - U.S. | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 52,058 52,058 51,902
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 52,058    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 51,902 52,058  
Pension Benefits | Common/Collective Trust Funds - U.S. | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | U.S. Large-Cap      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 14,305 14,305 17,792
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 14,305    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 17,792 14,305  
Pension Benefits | U.S. Large-Cap | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 14,305 14,305 $ 17,792
Number of sectors (in categories) | category     5
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 14,305    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 17,792 14,305  
Pension Benefits | U.S. Large-Cap | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 $ 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | U.S. Large-Cap | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | U.S. Mid-Cap      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 3,407 3,407 2,479
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 3,407    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 2,479 3,407  
Pension Benefits | U.S. Mid-Cap | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 3,407 3,407 2,479
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 3,407    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 2,479 3,407  
Pension Benefits | U.S. Mid-Cap | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | U.S. Mid-Cap | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | U.S. Small-Cap      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 260 260  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 260    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year   260  
Pension Benefits | U.S. Small-Cap | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 260 260  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 260    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year   260  
Pension Benefits | U.S. Small-Cap | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year   0  
Pension Benefits | U.S. Small-Cap | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year   0  
Pension Benefits | International equity securities      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 1,695 1,695 3,340
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 1,695    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 3,340 1,695  
Pension Benefits | International equity securities | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 1,695 1,695 3,340
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 1,695    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 3,340 1,695  
Pension Benefits | International equity securities | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | International equity securities | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Common/Collective Trust Funds - International      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 33,236 33,236 33,096
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 33,236    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 33,096 33,236  
Pension Benefits | Common/Collective Trust Funds - International | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Common/Collective Trust Funds - International | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 33,236 33,236 33,096
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 33,236    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 33,096 33,236  
Pension Benefits | Common/Collective Trust Funds - International | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Common/Collective Trust Funds      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 50,664 50,664 54,970
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 50,664    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 54,970 50,664  
Pension Benefits | Common/Collective Trust Funds | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Common/Collective Trust Funds | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 50,664 50,664 54,970
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 50,664    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 54,970 50,664  
Pension Benefits | Common/Collective Trust Funds | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Guaranteed Insurance Contract      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 9,960 9,960 9,714
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 9,960    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 9,714 9,960  
Pension Benefits | Guaranteed Insurance Contract | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Guaranteed Insurance Contract | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Guaranteed Insurance Contract | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 9,960 10,912 9,714
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 9,960 10,912  
Actual return on plan assets:      
Relating to assets still held at the reporting date 541 (106)  
Relating to assets sold during the period 14 25  
Purchases, Sales and Settlements (801) (871)  
Fair Value of Plan Assets at End of Year 9,714 9,960  
Pension Benefits | Hedge Funds      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 4,159 4,159  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 4,159    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year   4,159  
Pension Benefits | Hedge Funds | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year   0  
Pension Benefits | Hedge Funds | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year   0  
Pension Benefits | Hedge Funds | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 4,159 4,331 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 4,159 4,331  
Actual return on plan assets:      
Relating to assets still held at the reporting date (67) (172)  
Relating to assets sold during the period 0 0  
Purchases, Sales and Settlements (4,092) 0  
Fair Value of Plan Assets at End of Year 0 4,159  
Pension Benefits | Private Equity Funds      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 4,312 4,312 5,100
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 4,312    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 5,100 4,312  
Pension Benefits | Private Equity Funds | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Private Equity Funds | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Private Equity Funds | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 4,312 3,616 5,100
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 4,312 3,616  
Actual return on plan assets:      
Relating to assets still held at the reporting date (140) (302)  
Relating to assets sold during the period 245 429  
Purchases, Sales and Settlements 683 569  
Fair Value of Plan Assets at End of Year 5,100 4,312  
Pension Benefits | Real Estate      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 8,515 8,515 9,195
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 8,515    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 9,195 8,515  
Pension Benefits | Real Estate | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Real Estate | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Real Estate | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 8,515 7,476 9,195
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 8,515 7,476  
Actual return on plan assets:      
Relating to assets still held at the reporting date 680 1,039  
Relating to assets sold during the period 0 0  
Purchases, Sales and Settlements 0 0  
Fair Value of Plan Assets at End of Year 9,195 8,515  
Pension Benefits | Cash      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 35 35 63
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 35    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 63 35  
Pension Benefits | Cash | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 35 35 63
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 35    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 63 35  
Pension Benefits | Cash | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Cash | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Common/Collective Trust Funds      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 858 858 460
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 858    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 460 858  
Pension Benefits | Common/Collective Trust Funds | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Common/Collective Trust Funds | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 858 858 460
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 858    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 460 858  
Pension Benefits | Common/Collective Trust Funds | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | STIF-Type Instrument      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 1,360 1,360 1,431
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 1,360    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 1,431 1,360  
Pension Benefits | STIF-Type Instrument | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | STIF-Type Instrument | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 1,360 1,360 1,431
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 1,360    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 1,431 1,360  
Pension Benefits | STIF-Type Instrument | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 47,759 43,222 50,532
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 47,759 43,222  
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 50,532 47,759  
Other Postretirement Benefits | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 3,911 3,911 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 3,911    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 3,911  
Other Postretirement Benefits | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 43,848 43,848 50,532
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 43,848    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 50,532 43,848  
Other Postretirement Benefits | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year $ 0 0  
Other Postretirement Benefits | U.S. equity securities | Minimum      
Actual return on plan assets:      
Target plan allocation 30.00%    
Other Postretirement Benefits | U.S. equity securities | Maximum      
Actual return on plan assets:      
Target plan allocation 43.00%    
Other Postretirement Benefits | Common/Collective Trust Funds - U.S.      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets $ 13,522 13,522 14,878
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 13,522    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 14,878 13,522  
Other Postretirement Benefits | Common/Collective Trust Funds - U.S. | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Common/Collective Trust Funds - U.S. | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 13,522 13,522 14,878
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 13,522    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 14,878 13,522  
Other Postretirement Benefits | Common/Collective Trust Funds - U.S. | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Mutual Fund - U.S.      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 1,309 1,309  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 1,309    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year   1,309  
Other Postretirement Benefits | Mutual Fund - U.S. | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 1,309 1,309  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 1,309    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year   1,309  
Other Postretirement Benefits | Mutual Fund - U.S. | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year   0  
Other Postretirement Benefits | Mutual Fund - U.S. | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year $ 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year   0  
Other Postretirement Benefits | International equity securities | Minimum      
Actual return on plan assets:      
Target plan allocation 20.00%    
Other Postretirement Benefits | International equity securities | Maximum      
Actual return on plan assets:      
Target plan allocation 30.00%    
Other Postretirement Benefits | Common/Collective Trust Funds - International      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets $ 8,313 8,313 8,674
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 8,313    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 8,674 8,313  
Other Postretirement Benefits | Common/Collective Trust Funds - International | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Common/Collective Trust Funds - International | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 8,313 8,313 8,674
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 8,313    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 8,674 8,313  
Other Postretirement Benefits | Common/Collective Trust Funds - International | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Mutual Funds - International      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 983 983  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 983    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year   983  
Other Postretirement Benefits | Mutual Funds - International | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 983 983  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 983    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year   983  
Other Postretirement Benefits | Mutual Funds - International | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year   0  
Other Postretirement Benefits | Mutual Funds - International | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year $ 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year   0  
Other Postretirement Benefits | Fixed income investments | Minimum      
Actual return on plan assets:      
Target plan allocation 32.00%    
Other Postretirement Benefits | Fixed income investments | Maximum      
Actual return on plan assets:      
Target plan allocation 42.00%    
Other Postretirement Benefits | Common/Collective Trust Funds      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets $ 13,187 13,187 13,537
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 13,187    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 13,537 13,187  
Other Postretirement Benefits | Common/Collective Trust Funds | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Common/Collective Trust Funds | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 13,187 13,187 13,537
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 13,187    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 13,537 13,187  
Other Postretirement Benefits | Common/Collective Trust Funds | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Mutual Funds - Bonds      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 1,441 1,441  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 1,441    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year   1,441  
Other Postretirement Benefits | Mutual Funds - Bonds | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 1,441 1,441  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 1,441    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year   1,441  
Other Postretirement Benefits | Mutual Funds - Bonds | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year   0  
Other Postretirement Benefits | Mutual Funds - Bonds | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year $ 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year   0  
Other Postretirement Benefits | Other investments | Minimum      
Actual return on plan assets:      
Target plan allocation 0.00%    
Other Postretirement Benefits | Other investments | Maximum      
Actual return on plan assets:      
Target plan allocation 7.00%    
Other Postretirement Benefits | Mutual Funds - REITS      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets $ 152 152  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 152    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year   152  
Other Postretirement Benefits | Mutual Funds - REITS | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 152 152  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 152    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year   152  
Other Postretirement Benefits | Mutual Funds - REITS | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year   0  
Other Postretirement Benefits | Mutual Funds - REITS | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year   0  
Other Postretirement Benefits | Company Owned Life Insurance      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 8,826 8,826 13,443
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 8,826    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 13,443 8,826  
Other Postretirement Benefits | Company Owned Life Insurance | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Company Owned Life Insurance | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 8,826 8,826 13,443
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 8,826    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 13,443 8,826  
Other Postretirement Benefits | Company Owned Life Insurance | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Cash      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 26 26 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 26    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 26  
Other Postretirement Benefits | Cash | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 26 26 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 26    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 26  
Other Postretirement Benefits | Cash | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Cash | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 $ 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year $ 0 $ 0