v3.8.0.1
Investments - Summary of Investments Gross Unrealized Losses and Fair Value (Details) - USD ($)
$ in Thousands
Feb. 03, 2018
Jan. 28, 2017
Fair Value    
Less than 12 months $ 445,516 $ 339,525
12 months or more 103,298 18,810
Total 548,814 358,335
Unrealized Loss    
Less than 12 months (1,964) (1,176)
12 months or more (879) (29)
Total (2,843) (1,205)
U.S. government and agency debt    
Fair Value    
Less than 12 months 148,538 94,064
12 months or more 51,332 0
Total 199,870 94,064
Unrealized Loss    
Less than 12 months (298) (283)
12 months or more (346) 0
Total (644) (283)
Foreign government and agency debt    
Fair Value    
Less than 12 months 3,993 11,875
12 months or more 2,994 1,499
Total 6,987 13,374
Unrealized Loss    
Less than 12 months (1) (48)
12 months or more (16) (2)
Total (17) (50)
Municipal debt securities    
Fair Value    
Less than 12 months 1,969 17,450
12 months or more 0 1,248
Total 1,969 18,698
Unrealized Loss    
Less than 12 months (6) (47)
12 months or more 0 (2)
Total (6) (49)
Corporate debt securities    
Fair Value    
Less than 12 months 253,380 199,382
12 months or more 46,805 16,063
Total 300,185 215,445
Unrealized Loss    
Less than 12 months (1,514) (751)
12 months or more (485) (25)
Total (1,999) (776)
Asset backed securities    
Fair Value    
Less than 12 months 37,636 16,754
12 months or more 2,167 0
Total 39,803 16,754
Unrealized Loss    
Less than 12 months (145) (47)
12 months or more (32) 0
Total $ (177) $ (47)