Supplementary Cash Flow Information (Tables)

3 Months Ended

Mar. 31, 2013

Supplemental Cash Flow Elements [Abstract]

Schedule of supplementary cash flow information

(in millions)	For the Three Months Ended March 31,
	2013			2012
Change in working capital accounts:
Accounts receivable	$	(5.9	)	$	20.2
Product inventory	0.6			(17.4		)
Material and supplies inventory	(2.6		)	1.4
Prepaid expenses and other current assets	(7.8		)	(2.2		)
Income and mining taxes receivable	4.6			0.7
Accounts payable and accrued liabilities	(7.1		)	(17.8		)
Income and mining taxes payable	—			1.2
	$	(18.2	)	$	(13.9	)
Cash interest paid	$	7.9		$	0.2
Income and mining taxes (refund) paid, net	$	(1.1	)	$	2.2

Schedule of non-cash investing and financing activities

Non-cash Investing and Financing Activities

(in millions)	For the Three Months Ended March 31,
	2013		2012
Investing activities
Increase in capital expenditure accrual	$	—	$	20.3
Capitalized interest	$	23.7	$	6.6