EMPLOYEE BENEFIT PLANS - NET PENSION EXPENSE (DETAILS) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Qualified Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	$ 35.3	$ 32.3	$ 44.2
Interest cost	72.9	67.7	66.9
Expected return on assets	(88.2)	(70.9)	(51.3)
Amortization of prior service cost	(1.0)	(0.9)	4.3
Curtailment loss	0	0	0
Recognized actuarial loss	23.2	22.0	28.9
Net pension expense	42.2	50.2	93.0
Nonqualified Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1.0	0.8	0.7
Interest cost	2.2	2.1	2.2
Expected return on assets	0	0	0
Amortization of prior service cost	0.1	0.1	0.1
Curtailment loss	0.2	0	0
Recognized actuarial loss	0.4	0.1	0.1
Net pension expense	3.9	3.1	3.1
Anticipated funding in 2012	2
Postretirement Medical Benefits [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	6.0	5.3	5.6
Interest cost	7.2	6.7	7.8
Amortization of prior service cost	0.3	0	2.9
Recognized actuarial loss	1.2	0.3	0.8
Net pension expense	14.7	12.3	17.1
Anticipated funding in 2012	4
Minimum [Member] | Qualified Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Anticipated funding in 2012	35
Maximum [Member] | Qualified Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Anticipated funding in 2012	$ 50