6. Debt

Our debt consists of:

	March 31,			December 31,
(In thousands)	2018			2017
Senior secured term loans	$	123,750		$	243,750
Convertible subordinated notes due 2023	240,984			240,984
Convertible senior notes due 2025	192,500			192,500

Total debt	557,234			677,234
Unamortized debt discount and issuance costs	(72,643		)	(77,872		)
Current portion of senior secured term loan	—			(25,000		)

Net long-term debt	$	484,591		$	574,362

Prepayment of Senior Secured Term Loans

On February 28, 2018, we paid down the principal balance of the Term B Loan by $120.0 million. With the prepayment, we incurred a loss on the extinguishment of debt of $3.1 million representing unamortized debt issuance costs. The loss on the extinguishment of debt is presented as part of other income (expense), net in our consolidated statements of operations. As of March 31, 2018, the outstanding principal balance of the Term B Loan was reduced to $123.8 million.

Convertible Senior Notes Due 2025

In accordance with accounting guidance for debt with conversion and other options, we separately account for the liability and equity components of the 2025 Notes by allocating the proceeds between the liability component and the embedded conversion option (“equity component”) due to our ability to settle the conversion obligation of the 2025 Notes in cash, common stock or a combination of cash and common stock, at our option. The carrying amount of the liability component was calculated by measuring the fair value of a similar liability that does not have an associated convertible feature using the income approach. The allocation was performed in a manner that reflected our non-convertible debt borrowing rate for similar debt. The equity component of the 2025 Notes was recognized as a debt discount and represents the difference between the proceeds from the issuance of the 2025 Notes and the fair value of the liability of the 2025 Notes on the date of issuance. The excess of the principal amount of the liability component over its carrying amount (“debt discount”) is amortized to interest expense using the effective interest method. The equity component is not re-measured as long as it continues to meet the conditions for equity classification.

Our outstanding 2025 Notes balances as March 31, 2018, consisted of the following:

(In thousands)
Liability component
Principal	$	192,500
Debt discount and issuance costs, net	(66,740		)

Net carrying amount	$	125,760

Equity component, net	$	65,361

In connection with the issuance of the 2025 Notes, we incurred approximately $5.4 million of debt issuance costs, which primarily consisted of placement, legal and other professional fees, and allocated these costs to the liability and equity components based on the allocation of the proceeds. Of the total $5.4 million of debt issuance costs, $1.9 million were allocated to the equity component and recorded as a reduction to additional paid-in capital and $3.5 million were allocated to the liability component and recorded as a reduction to the carrying amount of the liability component on the consolidated balance sheet. The portion allocated to the liability component is amortized to interest expense over the expected life of the 2025 Notes using the effective interest method.

The following table sets forth total interest expense recognized related to the 2025 Notes for the three months ended March 31, 2018:

(In thousands)
Contractual interest expense	$	1,190
Amortization of debt issuance costs	123
Amortization of debt discount	1,479
Total interest and amortization expense	$	2,792

Debt Maturities

The aggregate scheduled maturities of our long-term debt as of March 31, 2018, are as follows:

(In thousands)
Years ending December 31:
2018 to 2021	$	—
2022	123,750
Thereafter	433,484

Total	$	557,234