XML 31 R43.htm IDEA: XBRL DOCUMENT v2.4.0.6
Bank Revolving Credit Facility (Details Textual) (USD $)
3 Months Ended
Apr. 30, 2012
Jan. 31, 2012
Apr. 30, 2012
Amended Credit Facility [Member]
Line of Credit Facility [Line Items]      
Maximum borrowings $ 450,000,000 $ 450,000,000 $ 450,000,000
Credit agreement maturity date     March 30, 2014 and one 12-month extension option
Interest rate of borrowings     LIBOR, subject to a floor of 100 basis points, plus 3.75%
Debt instrument variable rate basis     LIBOR
Debt instrument variable rate basis spread     3.75%
Debt instrument floor rate     1.00%
Amount of available borrowing that can be used for letters of credit or surety bonds     $ 100,000,000