Debt and Royalty Obligation (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Debt and royalty obligations
Current	$ 32,602	$ 63,317
Non-current	115,861	130,067
Interest expenses incurred for various debt instruments
Accretion of Franco Nevada royalty obligation	22,230	20,502	19,054
Amortization of debt issuance costs	2,050	4,047	989
Accretion of debt discount	2,324	2,543	9,094
Capitalized interest	(2,175)	(9,885)	(22,825)
Total interest expense	34,774	30,942	18,102
3.25% Convertible Senior Notes due March 2028 [Member]
Debt and royalty obligations
Current	0	0
Non-current	45,545	43,220
Interest expenses incurred for various debt instruments
Interest Expense, Debt	1,581	2,394	5,875
1.25% Convertible Senior Notes due January 2024 [Member]
Debt and royalty obligations
Current	0	1,859
Non-current	0	0
Interest expenses incurred for various debt instruments
Interest Expense, Debt	1	28	1,454
Senior Term Notes due December 2012 [Member]
Debt and royalty obligations
Current	0	15,000
Non-current	0	15,000
Interest expenses incurred for various debt instruments
Interest Expense, Debt	1,381	5,074	0
Kensington Term Facility [Member]
Debt and royalty obligations
Current	15,398	25,908
Non-current	60,424	48,322
Interest expenses incurred for various debt instruments
Interest Expense, Debt	4,383	2,017	85
Capital Lease Obligations [Member]
Debt and royalty obligations
Current	17,119	15,759
Non-current	9,891	23,483
Interest expenses incurred for various debt instruments
Interest Expense, Debt	1,620	2,122	1,149
Other debt obligations [Member]
Interest expenses incurred for various debt instruments
Interest Expense, Debt	1,379	1,423	818
Gold lease facility [Member]
Interest expenses incurred for various debt instruments
Interest Expense, Debt	0	677	1,522
Senior Secured Floating Rate Convertible Notes due 2012 [Member]
Interest expenses incurred for various debt instruments
Interest Expense, Debt	0	0	887
Bank Loans [Member]
Debt and royalty obligations
Current	85	4,791
Non-current	$ 0	$ 42