Convertible 3.75% Senior Notes

On December 16, 2014, the Company issued $125 million aggregate principal amount of 3.75% Convertible Senior Notes due 2019, or the Notes. On December 22, 2014, the Company announced the closing of the initial purchasers’ exercise in full of their option to purchase an additional $18.75 million aggregate principal amount. The Notes bear interest at a fixed rate of 3.75% per year, payable semiannually in arrears on June 15 and December 15 of each year, beginning on June 15, 2015 and mature on December 15, 2019, unless earlier repurchased, redeemed or converted. The Notes are convertible into shares of the Company’s common stock, cash or a combination thereof. On May 20, 2015, the Company received shareholder approval for the increase in the number of shares of common stock authorized and available for issuance upon conversion of the Notes.

The remaining unamortized discount and unamortized debt financing costs will be amortized over the remaining term of the debt of 2.0 years. At December 31, 2017 and December 31, 2016, the net carrying amount of the liability component and the remaining unamortized debt discount were as follows:



	December 31, 2017		December 31, 2016
	(in thousands)		(in thousands)

Face amount of the Notes	$	143,750	$	143,750
Unamortized discount	20,517		29,160
Debt issuance costs	2,256		3,199
Carrying amount of the Notes	$	120,977	$	111,391

Debt issuance costs associated with the Notes, include fees of $2.3 million at December 31, 2017 and $3.2 million at December 31, 2016.

For the years ended December 31, 2017, December 31, 2016 and December 31, 2015, the Company recorded the following expenses in relation to the Notes:



	December 31, 2017			December 31, 2016			December 31, 2015
	(in thousands)			(in thousands)			(in thousands)

Interest Expense at 3.75% coupon rate	$	5,391		$	5,391		$	5,391
Debt discount amortization	8,643			7,599			6,680
Amortization of deferred financing costs	942			828			728
Less: capitalized interest and other	(3,778		)	(514		)	559
Total interest expense	$	11,198		$	13,304		$	13,358