Convertible Senior Notes and Interest Expense

6 Months Ended

Jun. 30, 2019

Debt Disclosure [Abstract]

Convertible Senior Notes and Interest Expense

CONVERTIBLE SENIOR NOTES AND INTEREST EXPENSE

Overview of 2013 Convertible Notes

On December 17, 2013, we entered into an agreement for the sale of $120 million aggregate principal amount of 2.75% Convertible Senior Notes (the “2013 Convertible Notes”). During 2016 and 2017 we completed certain open market purchases to retire $79.5 million of principal. Maturity of the 2013 Convertible Notes occurred on December 15, 2018 and substantially all remaining notes were converted into our common stock at a rate of 95 shares per $1,000 principal units.

Components of Interest Expense on 2013 Convertible Notes

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		%