Derivatives and Fair Value Measurements (Details 1) (USD $) In Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Classification and amounts of pre-tax gains and losses related to the Company's non-trading hedges
Gain (loss) recognized in income on non-designated derivatives	$ 0	$ (8.5)	$ 0	$ (8.5)
Gain (loss) recognized in other comprehensive income on derivative (effective portion)	156.0	(201.5)	374.8	(112.0)
Gain (loss) reclassified from other comprehensive income into income (effective portion)	108.0	15.9	188.8	44.1
Gain (loss) reclassified from other comprehensive income into income (ineffective portion)	(0.7)	(1.7)	1.6	(0.7)
Cash flow hedges [Member] | Interest rate swaps [Member] | Interest expense [Member]
Classification and amounts of pre-tax gains and losses related to the Company's non-trading hedges
Gain (loss) recognized in income on non-designated derivatives	0	(8.5)	0	(8.5)
Gain (loss) recognized in other comprehensive income on derivative (effective portion)		(0.1)		0.8
Gain (loss) reclassified from other comprehensive income into income (effective portion)		0.7		(0.5)
Diesel fuel hedge contracts [Member] | Cash flow hedges [Member] | Operating costs and expenses [Member]
Classification and amounts of pre-tax gains and losses related to the Company's non-trading hedges
Gain (loss) recognized in income on non-designated derivatives	0	0	0	0
Gain (loss) recognized in other comprehensive income on derivative (effective portion)	(26.0)	(40.2)	72.9	(29.8)
Gain (loss) reclassified from other comprehensive income into income (effective portion)	11.9	(9.3)	20.0	(16.4)
Gain (loss) reclassified from other comprehensive income into income (ineffective portion)	(0.3)	(1.7)	2.1	(0.7)
Cash flow hedges [Member] | Explosives cash flow hedge contracts [Member] | Operating costs and expenses [Member]
Classification and amounts of pre-tax gains and losses related to the Company's non-trading hedges
Gain (loss) recognized in income on non-designated derivatives	0	0	0	0
Gain (loss) recognized in other comprehensive income on derivative (effective portion)	(0.9)	0.2	(0.8)	(3.6)
Gain (loss) reclassified from other comprehensive income into income (effective portion)	(0.1)	(2.6)	(0.1)	(4.9)
Gain (loss) reclassified from other comprehensive income into income (ineffective portion)	(0.4)	0	(0.5)	0
Foreign currency cash flow hedge contracts [Member] | Operating costs and expenses [Member]
Classification and amounts of pre-tax gains and losses related to the Company's non-trading hedges
Gain (loss) recognized in income on non-designated derivatives	0	0	0	0
Gain (loss) recognized in other comprehensive income on derivative (effective portion)	183.1	(161.4)	302.9	(79.4)
Gain (loss) reclassified from other comprehensive income into income (effective portion)	96.2	27.1	168.9	65.9
Foreign currency cash flow hedge contracts [Member] | Depreciation, depletion and amortization [Member] | Capital expenditure [Member]
Classification and amounts of pre-tax gains and losses related to the Company's non-trading hedges
Gain (loss) recognized in other comprehensive income on derivative (effective portion)	$ (0.2)		$ (0.2)