Convertible Senior Notes (Tables)

6 Months Ended

Jul. 31, 2018

Debt Disclosure [Abstract]

Convertible Debt

The Notes consisted of the following (in thousands):

	As of July 31, 2018
Liability:
Principal	$	575,000
Less: debt discount, net of amortization	(128,976		)
Less: debt issuance costs, net of amortization	(9,337		)
Net carrying amount of the Notes	$	436,687
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 and six months ended July 31, 2018 (in thousands):

	Three Months Ended July 31, 2018			Six Months Ended July 31, 2018
Amortization of debt discount	$	6,000		$	7,357
Amortization of debt issuance costs	434			532
Total amortization of debt discount and debt issuance costs	6,434			7,889
Contractual interest expense	181			224
Total interest expense related to the Notes	$	6,615		$	8,113
Effective interest rate of the liability component	5.6		%	5.6		%