During the three months ended March 31, 2021 the conditions allowing holders of the 2021 Notes to convert have been met. Further, the 2021 Notes became convertible at the option of the holders beginning on December 1, 2020 until the close of business on the second scheduled trading day immediately preceding the maturity date. As of March 31, 2021, the if-converted value of the 2021 Notes exceeded the principal value of those notes by $77.2 million. As a result of the 2021 Notes maturing on June 1, 2021, its net carrying amount was reclassified from long-term debt to short-term debt in the Company's condensed consolidated balance sheets during the three months ended June 30, 2020.

The net carrying amount of the liability component of the 2021 Notes was as follows (in thousands):

	March 31,			December 31,
	2021			2020
Principal	$	172,500		$	172,500
Unamortized discount		(1,285	)		(3,182	)
Unamortized issuance cost		(219	)		(542	)
Net carrying amount	$	170,996		$	168,776

The net carrying amount of the equity component of the 2021 Notes was as follows (in thousands):

	March 31,			December 31,
	2021			2020
Debt discount related to value of conversion option	$	32,945		$	32,945
Debt issuance cost		(1,179	)		(1,179	)
Net carrying amount	$	31,766		$	31,766

During the three months ended March 31, 2021 the conditions allowing holders of the 2025 Notes to convert have been met. Therefore, the 2025 Notes may be converted during the three months ended June 30, 2021. As of March 31, 2021, the if-converted value of the 2025 Notes exceeded the principal value of those notes by $62.3 million.

The net carrying amount of the liability component of the 2025 Notes was as follows (in thousands):

	March 31,			December 31,
	2021			2020
Principal	$	189,750		$	189,750
Unamortized discount		(41,810	)		(43,919	)
Unamortized issuance cost		(3,902	)		(4,060	)
Net carrying amount	$	144,038		$	141,771

The net carrying amount of the equity component of the 2025 Notes was as follows (in thousands):

	March 31,			December 31,
	2021			2020
Debt discount related to value of conversion option	$	49,947		$	49,947
Debt issuance cost		(1,607	)		(1,607	)
Net carrying amount	$	48,340		$	48,340

The following table sets forth the interest expense recognized related to the 2021 Notes and the 2025 Notes (in thousands):

	Three Months Ended
	March 31,
	2021		2020
Contractual interest expense	$	2,059	$	755
Amortization of debt discount		4,006		1,783
Amortization of debt issuance costs		481		287
Total interest expense	$	6,546	$	2,825