Convertible Senior Notes (Tables)

3 Months Ended

Apr. 30, 2019

Debt Disclosure [Abstract]

Convertible Debt

The Notes consisted of the following (in thousands):

	As of April 30, 2019
Liability:
Principal	$	575,000
Less: debt discount, net of amortization	(110,670		)
Less: debt issuance costs, net of amortization	(8,012		)
Net carrying amount of the Notes	$	456,318
Stockholders' equity:
Allocated value of the conversion feature	$	136,333
Less: debt issuance costs	(3,068		)
Additional paid-in capital	$	133,265

Interest Expense

The following table sets forth total interest expense recognized related to the Notes for the three months ended April 30, 2018 and 2019 (in thousands):

	Three Months Ended April 30, 2018			Three Months Ended April 30, 2019
Amortization of debt discount	$	1,357		$	6,052
Amortization of debt issuance costs	98			438
Total amortization of debt discount and debt issuance costs	1,455			6,490
Contractual interest expense	43			177
Total interest expense related to the Notes	$	1,498		$	6,667
Effective interest rate of the liability component	5.6		%	5.6		%