Annual report pursuant to Section 13 and 15(d)

PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Components Of Net Periodic Benefit Cost) (Details)

v3.3.1.900
PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Components Of Net Periodic Benefit Cost) (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets $ 193.4 $ 188.1 $ 169.8
Pension Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Actuarial Gain (Loss) 20.8 14.0 27.0
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements and Curtailments 0.2 1.4 0.0
Defined Benefit Plan, Fair Value of Plan Assets 700.6 749.8 712.5
Service cost 22.7 26.1 32.9
Interest cost (37.7) (40.3) (36.4)
Expected return on plan assets (59.8) (58.1) (52.3)
Amortization:      
Prior service costs (credits) 2.3 2.5 2.8
Net actuarial loss 21.0 15.4 27.0
Net periodic benefit cost 23.9 26.2 46.8
Effect of Curtailment (1.2) 0.0 0.0
Current year actuarial (gain)/loss (0.7) 109.7 (128.0)
Amortization of net loss 21.0 15.4 27.0
Current year prior service cost 0.0 0.0 0.8
Amortization of prior service (cost) credit (2.3) (2.5) (2.8)
Total recognized in other comprehensive income (25.2) 91.8 (157.0)
Total recognized in net periodic cost and other comprehensive income (1.3) 118.0 (110.2)
Defined Benefit Plan, Benefit Obligation (910.8) (998.0) (891.2)
Defined Benefit Plan, Funded Status of Plan (210.2) (248.2)  
Other Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Actuarial Gain (Loss) 6.6 4.5 10.2
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements and Curtailments 0.0 0.0 0.0
Defined Benefit Plan, Fair Value of Plan Assets 250.6 269.3 251.8
Service cost 6.4 1.8 4.0
Interest cost (13.4) (11.9) (12.6)
Expected return on plan assets (18.3) (17.1) (20.0)
Amortization:      
Prior service costs (credits) (3.7) (3.6) (3.6)
Net actuarial loss 6.6 4.5 10.2
Net periodic benefit cost 4.4 (2.5) 3.2
Effect of Curtailment 0.0 0.0 0.0
Current year actuarial (gain)/loss 0.2 22.2 (68.6)
Amortization of net loss 6.6 4.5 10.2
Current year prior service cost 0.0 (0.9) 0.0
Amortization of prior service (cost) credit 3.7 3.6 3.6
Total recognized in other comprehensive income (2.7) 20.4 (75.2)
Total recognized in net periodic cost and other comprehensive income 1.7 17.9 (72.0)
Defined Benefit Plan, Benefit Obligation (266.0) (295.8) $ (265.1)
Defined Benefit Plan, Funded Status of Plan (15.4) (26.5)  
Salaried Employees [Member] | Pension Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 258.3 288.3  
Amortization:      
Defined Benefit Plan, Benefit Obligation (340.0) (379.2)  
Defined Benefit Plan, Funded Status of Plan (81.7) (90.9)  
Salaried Employees [Member] | Other Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 0.0 0.0  
Amortization:      
Defined Benefit Plan, Benefit Obligation (38.2) (41.6)  
Defined Benefit Plan, Funded Status of Plan (38.2) (41.6)  
Hourly Employees [Member] | Pension Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 436.7 454.9  
Amortization:      
Defined Benefit Plan, Benefit Obligation (558.6) (603.9)  
Defined Benefit Plan, Funded Status of Plan (121.9) (149.0)  
Hourly Employees [Member] | Other Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 250.6 269.3  
Amortization:      
Defined Benefit Plan, Benefit Obligation (227.8) (254.2)  
Defined Benefit Plan, Funded Status of Plan 22.8 15.1  
Mining Employees [Member] | Pension Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 5.6 6.6  
Amortization:      
Defined Benefit Plan, Benefit Obligation (8.6) (9.2)  
Defined Benefit Plan, Funded Status of Plan (3.0) (2.6)  
Supplemental Executive Retirement Plan S E R P [Member] | Pension Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Fair Value of Plan Assets 0.0 0.0  
Amortization:      
Defined Benefit Plan, Benefit Obligation (3.6) (5.7)  
Defined Benefit Plan, Funded Status of Plan $ (3.6) $ (5.7)