Debt (Tables)

6 Months Ended

Jun. 30, 2018

Schedule of outstanding debt obligations

Our outstanding debt obligations as of June 30, 2018 and December 31, 2017 consisted of the following (in thousands):



	June 30, 2018		December 31, 2017
2023 Senior Notes	$	466,906	$	466,291
2022 Convertible Notes	254,902		248,194
2019 Convertible Notes	20,727		20,198
Total long-term debt	742,535		734,683
Less: current maturities	20,727		—
Long-term debt, net of current maturities	$	721,808	$	734,683

Schedule of outstanding convertible debt

The outstanding balances of our Convertible Notes as of June 30, 2018 consisted of the following (in thousands):



	2022 Convertible Notes		2019 Convertible Notes		Total
Liability component:
Principal	$	320,000	$	21,417	$	341,417
Less: debt discount and issuance costs, net	65,098		690		65,788
Net carrying amount	$	254,902	$	20,727	$	275,629
Equity Component	$	72,576	$	9,905	$	82,481

Schedule of total interest expense recognized related to the convertible debt

The following table sets forth total interest expense recognized related to the Convertible Notes during the three and six months ended June 30, 2018 and 2017 (in thousands):



	Three Months Ended June 30,				Six Months Ended June 30,
	2018		2017		2018		2017
Contractual interest expense	$	2,734	$	1,943	$	5,468	$	3,193
Amortization of debt issuance costs	347		321		685		596
Amortization of debt discount	3,313		2,716		6,550		4,644
Total interest expense	$	6,394	$	4,980	$	12,703	$	8,433

Schedule of future annual principal payments on long-term debt

Future annual principal payments on our long-term debt as of June 30, 2018 were as follows (in thousands):



Period	Future Annual Principal Payments
Remainder of Year Ending December 31, 2018	$	—
Year Ending December 31, 2019	21,417
Year Ending December 31, 2020	—
Year Ending December 31, 2021	—
Year Ending December 31, 2022	320,000
Thereafter	475,000
Total	$	816,417