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Debt (Senior Notes) (Narrative) (Details) - Senior Notes - USD ($)
1 Months Ended
Sep. 30, 2012
Jan. 31, 2016
Jan. 31, 2015
Debt Instrument [Line Items]      
Debt, face value $ 350,000,000 $ 350,000,000 $ 350,000,000
Debt, stated interest rate in percentage 3.75%    
Proceeds from issuance of long-term debt $ 345,800,000    
Debt Instrument, Unamortized Discount 1,300,000    
Debt issuance costs $ 2,900,000    
Debt redemption price as a percent of principal amount 100.00%    
Debt Instrument, Maturity Date Sep. 21, 2017    
Treasury Rate      
Debt Instrument [Line Items]      
Discount rate, basis spread on Treasury Rate 5000.00%