Convertible Senior Notes and Interest Expense (Tables)

6 Months Ended

Jun. 30, 2019

Debt Disclosure [Abstract]

Components of the Interest Expense Recognized

The following table sets forth the components of interest expense recognized in the accompanying Condensed Consolidated Statements of Operations for the 2013 Convertible Notes. 

	Three Months Ended June 30, 2018			Six Months Ended June 30, 2018
Stated coupon interest expense	$	279		$	558
Amortization of debt issuance costs	62			124
Accretion of debt discount	545			1,079
Total	$	886		$	1,761
Effective interest rate	8.4		%	8.4		%