Debt (Convertible Senior Debentures) (Narrative) (Details) (USD $)	12 Months Ended
	Jan. 31, 2012	Jan. 31, 2011	Jan. 31, 2010
Convertible Senior Debentures [Member]
Debt Instrument [Line Items]
Convertible senior debentures, issuance date	December 2006
Convertible senior debentures, face value	$ 0	$ 350,000,000
Convertible senior debentures, annual interest rate	2.75%
Borrowing rate of non-convertible debt	6.30%
Interest expense	9,000,000	9,600,000	9,600,000
Non-cash interest expense	$ 8,400,000	$ 10,300,000	$ 10,300,000
Loan Payable To Brightstar Corporation, Interest At LIBOR Plus 4.0% Payable Annually, Due September 2015 [Member]
Debt Instrument [Line Items]
Convertible senior debentures, issuance date	October 2010