Derivatives and Fair Value Measurements (Details 2) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014		Dec. 31, 2013
Gross amounts of recognized assets/liabilities [Member]
Derivative [Line Items]
Derivative assets, current	$ 21.3		$ 8.7
Derivative liabilities, current	77.8		215.8
Derivative assets, noncurrent	25.4		3.0
Derivative liabilities, noncurrent	62.7		264.1
Gross amounts of recognized assets/liabilities [Member] | Commodity swap contracts [Member]
Derivative [Line Items]
Derivative assets, current	9.7		8.7
Derivative liabilities, current	1.4		3.9
Derivative assets, noncurrent	8.0		2.8
Derivative liabilities, noncurrent	0.5		2.5
Gross amounts of recognized assets/liabilities [Member] | Foreign Currency Forward Contract [Member]
Derivative [Line Items]
Derivative assets, current	11.6		0
Derivative liabilities, current	76.4		211.9
Derivative assets, noncurrent	17.4		0.2
Derivative liabilities, noncurrent	62.2		261.6
Gross amounts offset in the condensed consolidated balance sheet [Member]
Derivative [Line Items]
Derivative assets, current	(10.9)		(2.3)
Derivative liabilities, current	(13.7)		(1.9)
Derivative assets, noncurrent	(17.1)		(1.1)
Derivative liabilities, noncurrent	(14.3)		(1.5)
Gross amounts offset in the condensed consolidated balance sheet [Member] | Commodity swap contracts [Member]
Derivative [Line Items]
Derivative assets, current	(0.7)		(2.3)
Derivative liabilities, current	(0.8)		(1.9)
Derivative assets, noncurrent	(0.5)		(0.9)
Derivative liabilities, noncurrent	(0.4)		(1.3)
Gross amounts offset in the condensed consolidated balance sheet [Member] | Foreign Currency Forward Contract [Member]
Derivative [Line Items]
Derivative assets, current	(10.2)		0
Derivative liabilities, current	(12.9)		0
Derivative assets, noncurrent	(16.6)		(0.2)
Derivative liabilities, noncurrent	(13.9)		(0.2)
Net amounts presented in the condensed consolidated balance sheet [Member]
Derivative [Line Items]
Derivative assets, current	10.4		6.4
Derivative liabilities, current	64.1		213.9
Derivative assets, noncurrent	8.3		1.9
Derivative liabilities, noncurrent	48.4		262.6
Net amounts presented in the condensed consolidated balance sheet [Member] | Commodity swap contracts [Member]
Derivative [Line Items]
Derivative assets, current	9.0		6.4
Derivative liabilities, current	0.6		2.0
Derivative assets, noncurrent	7.5		1.9
Derivative liabilities, noncurrent	0.1		1.2
Net amounts presented in the condensed consolidated balance sheet [Member] | Foreign Currency Forward Contract [Member]
Derivative [Line Items]
Derivative assets, current	1.4		0
Derivative liabilities, current	63.5		211.9
Derivative assets, noncurrent	0.8		0
Derivative liabilities, noncurrent	48.3		261.4
Derivatives not offset in the condensed consolidated balance sheet [Member]
Derivative [Line Items]
Derivative assets, current	(7.5)	[1]	(5.0)	[1]
Derivative liabilities, current	(7.4)	[1]	(5.4)	[1]
Derivative assets, noncurrent	(5.4)	[1]	(1.3)	[1]
Derivative liabilities, noncurrent	(5.5)	[1]	(0.9)	[1]
Net amount of derivatives not offset [Member]
Derivative [Line Items]
Derivative assets, current	2.9		1.4
Derivative liabilities, current	56.7		208.5
Derivative assets, noncurrent	2.9		0.6
Derivative liabilities, noncurrent	$ 42.9		$ 261.7

[1] Adjustments relate to the further netting of derivative contracts with a common counterparty across the Company's foreign currency, diesel fuel and explosives hedging strategy derivative contract portfolios that would be contractually enforceable in the event of default.