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Borrowing Arrangements - Additional Information (Detail) - USD ($)
3 Months Ended
Apr. 30, 2017
May 01, 2016
Debt Instrument [Line Items]    
Additional percentage over reference rate 2.00%  
Interest rate description Interest on unreimbursed amounts under the letter of credit facilities accrues at the lender's prime rate (or, if greater, the average rate on overnight federal funds plus one-half of one percent) plus 2.0%.  
Amount of borrowings under credit facility during period $ 45,000,000 $ 100,000,000
Maximum borrowing capacity under letter of credit facilities including additional borrowing capacity $ 70,000,000  
Letter of credit facilities, maturity date Aug. 26, 2017  
Outstanding letter of credit facilities $ 6,831,000  
Latest expiration date possible for future letters of credit Jan. 23, 2018  
Standby Letters of Credit    
Debt Instrument [Line Items]    
Amount issued but undrawn under credit facility $ 12,120,000  
Federal Funds    
Debt Instrument [Line Items]    
Additional percentage over reference rate 0.50%  
Unsecured Revolving Line Of Credit    
Debt Instrument [Line Items]    
Current borrowing capacity $ 500,000,000  
Maximum borrowing capacity including additional borrowing capacity $ 750,000,000  
Credit facility, maturity date Nov. 19, 2019  
Interest rate description We may elect interest rates calculated at (i) Bank of America's prime rate (or, if greater, the average rate on overnight federal funds plus one-half of one percent, or a rate based on LIBOR plus one percent) plus a margin based on our leverage ratio or (ii) LIBOR plus a margin based on our leverage ratio.  
Weighted average interest rate 2.01% 1.45%
Unsecured Revolving Line Of Credit | Maximum    
Debt Instrument [Line Items]    
Additional borrowing capacity $ 250,000,000  
Unsecured Revolving Line Of Credit | Federal Funds    
Debt Instrument [Line Items]    
Additional percentage over reference rate 0.50%  
Unsecured Revolving Line Of Credit | Libor    
Debt Instrument [Line Items]    
Additional percentage over reference rate 1.00%