Additional Balance Sheet Information (Details 1) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Reclamation liability
Balance at beginning of period	$ 9.3	$ 7.5
Settlement of obligations	(3.2)	(1.2)
Liabilities incurred and accretion expense	2.9	2.0
Foreign currency	0.3
Balance at end of period	$ 9.3	$ 8.3