Convertible Senior Notes (Tables)

3 Months Ended

Mar. 31, 2019

Debt Disclosure [Abstract]

Schedule of Components of Convertible Senior Notes

The Notes consist of the following (in thousands):

	As of
	March 31, 2019			December 31, 2018
Liability component:
Principal	$	115,000		$	115,000
Less: debt discount, net of amortization		(19,702	)		(20,903	)
Net carrying amount	$	95,298		$	94,097
Equity component (a)		22,094			22,094

a) Recorded in the consolidated balance sheet within additional paid-in capital, net of $0.8 million transaction costs in equity during the year ended December 31, 2017.

Summary of Total Interest Expense Recognized Related To Convertible Senior Notes

The following table sets forth total interest expense recognized related to the Notes (in thousands):

	Three months ended
	March 31, 2019		March 31, 2018
1.50% coupon	$	432	$	436
Amortization of debt discount and transaction costs		1,201		1,134
	$	1,633	$	1,570

Summary of Fair Value and Carrying Value of Convertible Senior Notes

As of March 31, 2019 and December 31, 2018, the fair value of the Notes, which was determined based on inputs that are observable in the market or that could be derived from, or corroborated with, observable market data, quoted price of the Notes in an over-the-counter market (Level 2), and carrying value of debt instruments (carrying value excludes the equity component of the Company’s convertible notes classified in equity) were as follows (in thousands):

	March 31, 2019				December 31, 2018
	Fair Value		Carrying Value		Fair Value		Carrying Value
Convertible senior notes	$	255,954	$	95,298	$	189,802	$	94,097