Convertible Senior Notes - Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Aug. 02, 2020	Jul. 31, 2019	Aug. 02, 2020	Jul. 31, 2019
Debt Instrument [Line Items]
Total amortization of debt discount and debt issuance costs			$ 14,125	$ 13,290
Convertible Senior Notes
Debt Instrument [Line Items]
Amortization of debt discount	$ 6,703	$ 6,341	13,171	12,393
Amortization of debt issuance costs	486	459	954	897
Total amortization of debt discount and debt issuance costs	7,189	6,800	14,125	13,290
Contractual interest expense	181	181	358	358
Total interest expense related to the Notes	$ 7,370	$ 6,981	$ 14,483	$ 13,648
Effective interest rate of the liability component	5.60%	5.60%	5.60%	5.60%

Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense.

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