Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Operating activities:
Net income	$ 12,572	$ 43,357
Non-cash elements included in net income:
Depreciation, depletion and amortization	11,269	12,327
Gain on sale of investments		(611)
Gain on disposition of properties, plants, equipment, and mineral interests	(28)
Provision for reclamation and closure costs	1,427	279
Stock compensation	558	377
Deferred income taxes	2,826	23,135
Amortization of loan origination fees	100	166
(Gain) loss on derivative contracts	12,140	(5,186)
Other non-cash charges, net	270	324
Change in assets and liabilities:
Accounts receivable	8,014	(13,395)
Inventories	1,948	1,310
Other current and non-current assets	549	1,683
Accounts payable and accrued liabilities	(5,580)	1,043
Accrued payroll and related benefits	(3,870)	(1,188)
Accrued taxes	2,890	(1,333)
Accrued reclamation and closure costs and other non-current liabilities	(3,659)	(1,378)
Cash provided by operating activities	41,426	60,910
Investing activities:
Additions to properties, plants, equipment and mineral interests	(24,652)	(21,831)
Proceeds from sale of investments		1,366
Proceeds from disposition of properties, plants and equipment	35	112
Purchases of investments		(3,200)
Changes in restricted cash and investment balances		5
Net cash used in investing activities	(24,617)	(23,548)
Financing activities:
Proceeds from exercise of stock options and warrants		4,739
Acquisition of treasury shares		(18)
Dividends paid to common shareholders	(3,566)
Dividends paid to preferred shareholders	(138)	(3,408)
Repayments of capital leases	(1,064)	(619)
Net cash (used) provided by financing activities	(4,768)	694
Change in cash and cash equivalents:
Net increase in cash and cash equivalents	12,041	38,056
Cash and cash equivalents at beginning of period	266,463	283,606
Cash and cash equivalents at end of period	278,504	321,662
Significant non-cash investing and financing activities:
Addition of capital lease obligations	4,417	1,065
Accounts payable change relating to capital additions	$ (2,126)	$ (3,488)