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Fair Value Measurements - Amortized Cost and Fair Market Value of Securities by Contractual Maturity (Details) - USD ($)
$ in Thousands
Feb. 03, 2018
Jan. 28, 2017
Jan. 30, 2016
Amortized Cost      
Mature in one year or less $ 31,500 $ 38,026  
Mature after one year through five years 25,451 26,691  
Total 56,951 64,717  
Fair Market Value      
Mature in one year or less 31,474 38,028  
Mature after one year through five years 25,335 26,640  
Total Fair Market Value 56,809 64,668  
Changes among the fair value levels      
Changes between Level 1 to Level 2, Assets 0 0 $ 0
Changes between Level 2 to Level 1, Assets $ 0 $ 0 $ 0