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Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Acquisition and subsequent event) (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended	12 Months Ended							0 Months Ended
	Dec. 24, 2013 Sherritt International Corporation [Member] mines	Dec. 31, 2013 Sherritt International Corporation [Member]	Dec. 31, 2013 Revolving Credit Facility [Member]	Dec. 24, 2013 Revolving Credit Facility [Member] Minimum [Member]	Dec. 24, 2013 Revolving Credit Facility [Member] Maximum [Member]	Dec. 24, 2013 Revolving Credit Facility [Member] Discretionary Increase [Member]	Dec. 31, 2013 Letter of Credit [Member]	Dec. 24, 2013 Letter of Credit [Member]	Feb. 07, 2014 Subsequent Event Senior Notes Due 2018	Jan. 10, 2014 Subsequent Event Letter of Credit [Member]
Business Acquisition [Line Items]
Number of mines	7
Percentage of voting interests acquired	50.00%
Purchase price	$ 435.0
Cash consideration	293.0
Cash bonding obligation									58.0
Assumption of capital lease obligation	142
Acquisition-related costs		2.9
Cash transaction costs									26.0
Line of credit facility maximum borrowing capacity			20.0	60.0	70.0	100.0	2.0	30.0		10.0
Senior secured note face amount									$ 425.0
Stated interest rate									10.75%
Issue price (as a percent of face value)									106.875%