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Pension and Retirement Savings Plan - Weighted-average Assumptions Used to Calculate Benefit Obligations and Net Periodic Benefit Cost (Details)
12 Months Ended
Jan. 31, 2019
Defined Benefit Plan Weighted Average Assumptions Used In Calculating Net Periodic Benefit Cost [Abstract]  
Discount rate 0.90%
Salary progression rate 1.10%
Expected long-term rate of return on plan assets 0.90%