Annual report pursuant to Section 13 and 15(d)

BENEFIT PLANS - Projected Benefit Obligation (Details)

v3.3.1.900
BENEFIT PLANS - Projected Benefit Obligation (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Pension Benefits      
Change in Benefit Obligation [Roll Forward]      
Projected benefit obligation at beginning of measurement year $ 799,594 $ 684,999  
Service cost 1,830 1,740 $ 25,122
Interest cost 31,937 32,398 30,112
Benefits paid (17,246) (16,221)  
Settlements (27,976) (27,045)  
Plan amendments 0 0  
Plan curtailments 0 0  
Medicare subsidies 0 0  
Actuarial assumptions and gains and losses (33,425) 123,723  
Total changes (44,880) 114,595  
Projected benefit obligation at end of measurement year 754,714 799,594 684,999
Post-Retirement Benefits      
Change in Benefit Obligation [Roll Forward]      
Projected benefit obligation at beginning of measurement year 15,963 25,669  
Service cost 0 0 0
Interest cost 506 856 862
Benefits paid (2,211) (3,401)  
Settlements (6,993) 0  
Plan amendments 0 (8,782)  
Plan curtailments 0 0  
Medicare subsidies 117 462  
Actuarial assumptions and gains and losses 643 1,159  
Total changes (7,938) (9,706)  
Projected benefit obligation at end of measurement year $ 8,025 $ 15,963 $ 25,669