Convertible Senior Notes (Tables)

3 Months Ended

Apr. 30, 2020

Debt Disclosure [Abstract]

Convertible Senior Notes

The net carrying amount of the liability and equity components for each of the Notes as of April 30, 2020 was as follows:

(In thousands)	2023 Notes		2025 Notes
Liability component:
Principal amount	$	1,265,000	$	862,500
Unamortized discount	(188,675)		(191,156)
Unamortized issuance costs	(7,363)		(5,260)
Net carrying amount	$	1,068,962	$	666,084
Equity component, net of purchase discounts and issuance costs	$	264,129	$	234,712

Schedule of Interest Expense

The following table sets forth the interest expense related to the Notes:

	Three Months Ended April 30,
(In thousands)	2020		2019
2023 Notes:
Coupon interest expense	$	1,581	$	1,581
Amortization of debt discount (conversion option)	12,418		11,595
Amortization of debt issuance costs and purchase discounts	485		453
Total interest expense related to the 2023 Notes	$	14,484	$	13,629
2025 Notes:
Coupon interest expense	$	2,426	$	2,426
Amortization of debt discount (conversion option)	7,312		6,771
Amortization of debt issuance costs and purchase discounts	201		186
Total interest expense related to the 2025 Notes	$	9,939	$	9,383