DEBT (Tables)

12 Months Ended

Dec. 31, 2019

Schedule of outstanding debt obligations

Our outstanding debt obligations as of December 31, 2019 and December 31, 2018 consisted of the following (in thousands):



	December 31,
	2019		2018
2022 Convertible Notes	$	277,034	$	261,933
2019 Convertible Notes	—		21,276
Total long-term debt	277,034		283,209
Less: current maturities	—		21,276
Long-term debt, net of current maturities	$	277,034	$	261,933

Schedule of outstanding convertible debt

The outstanding balances of our Convertible Notes as of December 31, 2019 consisted of the following (in thousands):



	2022 Convertible Notes
Liability component:
Principal	$	320,000
Less: debt discount and issuance costs, net	42,966
Net carrying amount	$	277,034
Gross equity component	$	72,576

Schedule of total interest expense recognized related to the convertible notes

The following table sets forth total interest expense recognized related to the 2022 Convertible Notes and 2019 Convertible Notes during 2019, 2018, and 2017 (in thousands):



	Years Ended December 31,
	2019		2018		2017
Contractual interest expense	$	10,467	$	10,935	$	8,961
Amortization of debt issuance costs	1,412		1,403		1,275
Amortization of debt discount	13,830		13,414		11,071
Total interest expense	$	25,709	$	25,752	$	21,307