Benefits (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Defined Benefit Plan Disclosure [Line Items]
Matching contributions under Savings Plans		$ 14,100,000	$ 13,800,000	$ 14,100,000
Weighted-Average assumptions used to determine net cost for year ended Dec. 31
Expected return on plan assets				8.25%
A one-percentage-point change in assumed health care cost trend rates effects
1% Increase, in assumed health care cost trend rates, Effect on, Post-retirement benefit obligation		31,900,000
1% Decrease, in assumed health care cost trend rates, Effect on, Post-retirement benefit obligation		(26,800,000)
1% Increase, in assumed health care cost trend rates, Effect on, Total of service and interest cost components		3,800,000
1% Decrease, in assumed health care cost trend rates, Effect on, Total of service and interest cost components		(3,100,000)
Benefits (Textuals) [Abstract]
Accumulated benefit obligation for all defined benefit plans		1,329,400,000	1,222,500,000
Health care cost trend rate up to specified age		65
Health care cost trend rate post specified age		65
Current pension plan target asset allocation in equity investments		45.00%
Current pension plan target asset allocation in fixed income investments		55.00%
Other Post-Retirement Employee Benefits target asset allocation in equity investments		60.00%
Other Post-Retirement Employee Benefits target asset allocation in fixed income investments		40.00%
Matching contributions under Savings Plans		14,100,000	13,800,000	14,100,000
Postemployment benefits liability		15,300,000
Pension, Qualified [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Funded Status of Plan		24,400,000	(71,700,000)
Pension, Non-Qualified [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Funded Status of Plan		(92,500,000)	(91,600,000)
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Amortization of Previously Unrecognized Benefit Costs	43,900,000
Net Periodic Benefit Cost
Service cost		15,900,000	23,700,000	23,300,000
Interest cost		67,600,000	68,400,000	72,300,000
Expected return on plan assets		(82,100,000)	(78,200,000)	(95,400,000)
Amortization of:
Transition obligation		0	0	0
Prior service cost (credit)		2,200,000	2,200,000	2,200,000
Actuarial loss		34,000,000	26,800,000	18,900,000
Curtailment (gain)		0	0	0
Net Periodic Benefit Cost		37,600,000	42,900,000	21,300,000
Weighted-Average assumptions used to determine benefit obligations as of Dec. 31
Discount rate		5.05%	5.60%	6.05%
Rate of compensation increase		4.00%	4.00%	4.00%
Weighted-Average assumptions used to determine net cost for year ended Dec. 31
Discount rate		5.60%	6.05%	6.50%
Expected return on plan assets		7.25%	7.25%	8.25%
Rate of compensation increase		4.00%	4.00%	4.00%
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		1,262,500,000	1,059,500,000	1,026,000,000
Employer contributions to defined benefit plan
Employer contributions		242,900,000	6,800,000
Expected benefit payments in future
2012		110,100,000
2013		101,300,000
2014		104,400,000
2015		103,600,000
2016		103,900,000
2017-2021		535,200,000
Pension Plans [Member] | Fair Value, Inputs, Level 1 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		681,800,000	400,900,000
Pension Plans [Member] | Fair Value, Inputs, Level 2 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		580,700,000	658,600,000
Pension Plans [Member] | Fair Value, Inputs, Level 3 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		0	0
Pension Plans [Member] | Cash And Cash Equivalents [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		8,500,000	21,100,000
Pension Plans [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		8,500,000	21,100,000
Pension Plans [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		0	0
Pension Plans [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		0	0
Pension Plans [Member] | U.S. Equity [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		455,100,000	464,700,000
Pension Plans [Member] | U.S. Equity [Member] | Fair Value, Inputs, Level 1 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		455,100,000	217,200,000
Pension Plans [Member] | U.S. Equity [Member] | Fair Value, Inputs, Level 2 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		0	247,500,000
Pension Plans [Member] | U.S. Equity [Member] | Fair Value, Inputs, Level 3 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		0	0
Pension Plans [Member] | International Equity [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		134,300,000	102,700,000
Pension Plans [Member] | International Equity [Member] | Fair Value, Inputs, Level 1 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		100,400,000	81,100,000
Pension Plans [Member] | International Equity [Member] | Fair Value, Inputs, Level 2 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		33,900,000	21,600,000
Pension Plans [Member] | International Equity [Member] | Fair Value, Inputs, Level 3 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		0	0
Pension Plans [Member] | U.S. Bonds [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		579,700,000	411,200,000
Pension Plans [Member] | U.S. Bonds [Member] | Fair Value, Inputs, Level 1 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		76,900,000	49,700,000
Pension Plans [Member] | U.S. Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		502,800,000	361,500,000
Pension Plans [Member] | U.S. Bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		0	0
Pension Plans [Member] | International Bonds [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		84,900,000	59,800,000
Pension Plans [Member] | International Bonds [Member] | Fair Value, Inputs, Level 1 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		40,900,000	31,800,000
Pension Plans [Member] | International Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		44,000,000	28,000,000
Pension Plans [Member] | International Bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		0	0
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Amortization of Previously Unrecognized Benefit Costs	5,500,000
Net Periodic Benefit Cost
Service cost		10,400,000	11,200,000	8,700,000
Interest cost		20,800,000	21,200,000	20,500,000
Expected return on plan assets		(16,900,000)	(14,300,000)	(13,600,000)
Amortization of:
Transition obligation		300,000	300,000	300,000
Prior service cost (credit)		(1,900,000)	(11,900,000)	(12,600,000)
Actuarial loss		6,200,000	10,800,000	8,900,000
Curtailment (gain)		0	(400,000)	0
Net Periodic Benefit Cost		18,900,000	16,900,000	12,200,000
Weighted-Average assumptions used to determine benefit obligations as of Dec. 31
Discount rate		5.20%	5.70%	5.75%
Weighted-Average assumptions used to determine net cost for year ended Dec. 31
Discount rate		5.70%	5.75%	6.50%
Expected return on plan assets		7.50%	7.50%	8.25%
Assumed health care cost trend rates as of Dec. 31
Health care cost trend rate assumed for next year, Pre 65		0.08	0.075	0.075
Health care cost trend rate assumed for next year, Post 65		0.12	0.16	0.20
Rate that the cost trend rate gradually adjusts to		0.050	0.050	0.050
Year that the rate reaches the rate it is assumed to remain at (Pre 65 / Post 65)		2017/2017	2015/2016	2015/2016
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		255,400,000	216,700,000	202,600,000
Employer contributions to defined benefit plan
Employer contributions		48,400,000	4,900,000	24,300,000
Expected benefit payments in future
2012		20,200,000
2013		20,800,000
2014		22,200,000
2015		23,500,000
2016		24,700,000
2017-2021		136,400,000
OPEB [Member] | Fair Value, Inputs, Level 1 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		165,000,000	72,100,000
OPEB [Member] | Fair Value, Inputs, Level 2 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		90,400,000	144,600,000
OPEB [Member] | Fair Value, Inputs, Level 3 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		0	0
OPEB [Member] | Cash And Cash Equivalents [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		2,400,000	1,500,000
OPEB [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		2,400,000	1,500,000
OPEB [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		0	0
OPEB [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		0	0
OPEB [Member] | U.S. Equity [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		113,600,000	121,700,000
OPEB [Member] | U.S. Equity [Member] | Fair Value, Inputs, Level 1 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		113,600,000	41,600,000
OPEB [Member] | U.S. Equity [Member] | Fair Value, Inputs, Level 2 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		0	80,100,000
OPEB [Member] | U.S. Equity [Member] | Fair Value, Inputs, Level 3 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		0	0
OPEB [Member] | International Equity [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		34,400,000	6,600,000
OPEB [Member] | International Equity [Member] | Fair Value, Inputs, Level 1 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		32,100,000	5,200,000
OPEB [Member] | International Equity [Member] | Fair Value, Inputs, Level 2 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		2,300,000	1,400,000
OPEB [Member] | International Equity [Member] | Fair Value, Inputs, Level 3 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		0	0
OPEB [Member] | U.S. Bonds [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		91,200,000	81,200,000
OPEB [Member] | U.S. Bonds [Member] | Fair Value, Inputs, Level 1 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		8,200,000	21,800,000
OPEB [Member] | U.S. Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		83,000,000	59,400,000
OPEB [Member] | U.S. Bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		0	0
OPEB [Member] | International Bonds [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		13,800,000	5,700,000
OPEB [Member] | International Bonds [Member] | Fair Value, Inputs, Level 1 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		8,700,000	2,000,000
OPEB [Member] | International Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		5,100,000	3,700,000
OPEB [Member] | International Bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Summary of fair value of pension plan assets by asset category within the fair value hierarchy
Fair value of our pension plan assets		0	0
Expected Medicare Part D Subsidy [Member]
Expected benefit payments in future
2012		(900,000)
2013		0
2014		0
2015		0
2016		0
2017-2021		0
Pension, Qualified [Member] | Pension Plans [Member]
Employer contributions to defined benefit plan
Employer contributions		236,400,000	0	270,000,000
Pension, Non-Qualified [Member] | Pension Plans [Member]
Employer contributions to defined benefit plan
Employer contributions		$ 6,500,000	$ 6,800,000	$ 5,800,000
Cash Balance Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Loss Contingency Range Of Possible Loss, Per Share, Maximum		$ 0.04