CONVERTIBLE SENIOR NOTES (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	1 Months Ended	3 Months Ended			1 Months Ended	3 Months Ended
	Apr. 08, 2013	Feb. 28, 2013	Feb. 28, 2012	Nov. 30, 2012	Apr. 30, 2012 Convertible Debt	Feb. 28, 2013 Convertible Debt	Feb. 28, 2013 Fair Value, Inputs, Level 2
Debt Disclosure [Line Items]
Principal amount of senior note					$ 600,000,000
Debt instrument, fixed annual interest rate					2.25%
Principal amount of note					1,000
Convertible senior notes conversion ratio (shares)					19.7750
Convertible senior notes initial conversion price					$ 50.57
Convertible senior notes minimum number of days out of thirty consecutive trading days that common stock price exceeded conversion price						20 days
Convertible senior notes number of consecutive trading days						30 days
Convertible senior notes minimum percentage of conversion price						130.00%
Consecutive trading day period						5 days
Convertible senior notes maximum percentage of trading price						98.00%
Stock observation period						35 days
Payments classification for shares repurchased		21,871,000	67,525,000			121,000,000
Shares repurchased (in shares)	1.4	1.0				3.6
Debt effective interest rate						5.50%
Debt discount, before tax					84,600,000	71,700,000
Debt discount, after tax						52,600,000
Convertible senior notes, net		528,285,000		524,466,000		528,300,000
Deferred issuance costs					15,600,000
Deferred issuance costs, liability component					13,400,000
Deferred issuance costs, equity component					2,200,000
Deferred issuance costs, equity component net of tax					1,400,000
Interest expense		8,782,000	1,465,000			7,900,000
Convertible note contractual coupon interest						3,400,000
Amortization of debt discount						3,800,000
Amortization of debt issuance costs						700,000
Convertible senior notes, fair value disclosures							$ 586,000,000