Convertible Senior Notes - (Tables)

6 Months Ended

Jul. 31, 2019

Debt Disclosure [Abstract]

Convertible Debt

The Notes consisted of the following (in thousands):

	As of July 31, 2019
Liability:
Principal	$	575,000
Less: debt discount, net of amortization	(104,329		)
Less: debt issuance costs, net of amortization	(7,553		)
Net carrying amount of the Notes	$	463,118
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 three and six months ended July 31, 2018 and 2019 (in thousands):

	Three Months Ended July 31,						Six Months Ended July 31,
	2018			2019			2018			2019
Amortization of debt discount	$	6,000		$	6,341		$	7,357		$	12,393
Amortization of debt issuance costs	434			459			532			897
Total amortization of debt discount and debt issuance costs	6,434			6,800			7,889			13,290
Contractual interest expense	181			181			224			358
Total interest expense related to the Notes	$	6,615		$	6,981		$	8,113		$	13,648
Effective interest rate of the liability component	5.6		%	5.6		%	5.6		%	5.6		%