BASIS OF PRESENTATION AND ACCOUNTING POLICIES (Details 4)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Options to purchase shares of common stock and restricted stock units
Potential common shares excluded from the calculation of diluted net income (loss) per share
Antidilutive securities related to potential shares excluded from calculation of net income (loss) per share (in shares)	2,591,295	3,091,164	2,546,822	2,775,786
2.25% Convertible subordinated notes due June 2013 (2.25% Notes)
Potential common shares excluded from the calculation of diluted net income (loss) per share
Antidilutive securities related to potential shares excluded from calculation of net income (loss) per share (in shares)		2,909,940		3,229,658
2.50% convertible senior notes due November 2017 (2.50% Notes)
Potential common shares excluded from the calculation of diluted net income (loss) per share
Antidilutive securities related to potential shares excluded from calculation of net income (loss) per share (in shares)	15,424,084		15,424,118