SECURITIES REPURCHASE PROGRAM (Details) (USD $)	1 Months Ended		3 Months Ended	6 Months Ended			1 Months Ended
	May 31, 2011	Nov. 30, 2010	Jun. 30, 2011	Jun. 30, 2011	Jun. 30, 2011 5.375% Convertible notes due August 2014	Jun. 30, 2011 5.375% Convertible notes due August 2014 Repurchase of debt	Mar. 31, 2011 Common shares	Jun. 30, 2011 Common shares
Securities repurchase program
Aggregate maximum amount authorized under the "securities repurchase program"		$ 1,500,000,000
Aggregate principal amount of notes repurchased					109,000,000
Stated interest rate (as a percent)					5.375%
Aggregate purchase price of convertible notes			199,788,000	339,013,000	344,000,000
Carrying amount of convertible notes					93,300,000
Unamortized deferred financing costs					3,100,000
Estimated fair value of convertible notes					111,600,000
Loss on extinguishment of debt			(14,748,000)	(23,010,000)	18,300,000
Difference between the estimated fair value and the repurchase price of securities					232,400,000
Difference between the estimated fair value and the purchase price of securities charged to additional paid-in capital					17,600,000
Difference between the estimated fair value and the purchase price of securities charged to accumulated deficit					214,800,000
Estimated amount receivable in relation to withholding taxes on repurchase								24,200,000
Accreted interest on repurchase of convertible debt			2,712,000	5,001,000	5,000,000
Premium above the carrying value on repurchase of convertible debt					15,200,000
Aggregate principal amount of the 5.375% Convertible Notes repurchased in connection with the securities repurchase program					235,200,000	11,400,000
Aggregate consideration on the 5.375% Convertible Notes repurchased in connection with the securities repurchase program					603,300,000	41,700,000
Common shares repurchased (in shares)							7,366,419
Aggregate repurchase price of entity's common shares repurchased	224,814,000		224,814,000	499,564,000			274,800,000
Aggregate common shares repurchased in connection with the securities repurchase program (in shares)								14,169,599
Aggregate consideration on Company's common shares repurchased in connection with the securities repurchase program								$ 559,700,000