6. Long-term Debt

1.75% Convertible Senior Notes and Convertible Note Hedge and Warrant Transactions

In June 2016, the Company issued $150.0 million aggregate principal amount of 1.75% convertible senior notes due 2021 in a registered underwritten public offering and an additional $22.5 million aggregate principal amount of such notes pursuant to the exercise in full of the over-allotment options of the underwriters (the 2021 Notes). The interest rates are fixed at 1.75% per annum and are payable semi-annually in arrears on June 1 and December 1 of each year, commencing on December 1, 2016. The total net proceeds from the debt offering, after deducting initial purchase discounts and debt issuance costs, were approximately $166.2 million.

Each $1,000 principal amount of the 2021 Notes will initially be convertible into 10.3770 shares of the Company’s common stock, which is equivalent to an initial conversion price of approximately $96.37 per share, subject to adjustment upon the occurrence of specified events. The 2021 Notes will be convertible at the option of the holders at any time prior to the close of business on the business day immediately preceding December 1, 2020, only under the following circumstances: (1) during any calendar quarter commencing after the calendar quarter ending on September 30, 2016 (and only during such calendar quarter), if the last reported sale price of the Company’s common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price on each applicable trading day; (2) during the five business day period after any ten consecutive trading day period (the measurement period) in which the trading price (as defined in the indenture to the 2021 Notes) per $1,000 principal amount of notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of the Company’s common stock and the conversion rate on each such trading day; or (3) upon the occurrence of specified corporate events. On or after December 1, 2020 until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may convert their 2021 Notes at any time, regardless of the foregoing circumstances. Upon conversion, the Company will pay or deliver, as the case may be, cash, shares of the Company’s common stock or a combination of cash and shares of the Company’s common stock, at the Company’s election. If the Company undergoes a fundamental change prior to the maturity date, holders of the notes may require the Company to repurchase for cash all or any portion of their notes at a repurchase price equal to 100% of the principal amount of the notes to be repurchased, plus accrued and unpaid interest to, but excluding, the fundamental change repurchase date. In addition, if specific corporate events occur prior to the applicable maturity date, the Company will increase the conversion rate for a holder who elects to convert their notes in connection with such a corporate event in certain circumstances. It is the Company’s current intent and policy to settle conversions through combination settlement with a specified dollar amount per $1,000 principal amount of notes of $1,000. During the three months ended March 31, 2017, the conditions allowing holders of the 2021 Notes to convert have not been met. The 2021 Notes are therefore not convertible during the three months ended June 30, 2017 and are classified as long-term debt. Should the sale price condition be met in a future quarter, the 2021 Notes will be convertible at the holders’ option during the immediately following quarter. As of March 31, 2017, the if-converted value of the 2021 Notes did not exceed the principal value of those notes.

In accounting for the issuance of the convertible senior notes, the Company separated the 2021 Notes into liability and equity components. The carrying amount of the liability component was calculated by measuring the fair value of a similar debt instrument that does not have an associated convertible feature. The carrying amount of the equity component representing the conversion option was $32.9 million and was determined by deducting the fair value of the liability component from the par value of the 2021 Notes. The equity component is not remeasured as long as it continues to meet the conditions for equity classification. The excess of the principal amount of the liability component over its carrying amount ("debt discount") is amortized to interest expense over the term of the 2021 Notes expense at an effective interest rate of 6.29% over the contractual terms of the notes.

In accounting for the debt issuance costs of $6.2 million related to the 2021 Notes, the Company allocated the total amount incurred to the liability and equity components of the 2021 Notes based on their relative values. Issuance costs attributable to the liability component were $5.0 million and will be amortized to interest expense using the effective interest method over the contractual terms of the 2021 Notes. Issuance costs attributable to the equity component were netted with the equity component in stockholders’ equity.

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

	March 31,			December 31,
	2017			2016
Principal	$	172,500		$	172,500
Unamortized discount		(28,303	)		(29,783	)
Unamortized issuance cost		(4,377	)		(4,577	)
Net carrying amount	$	139,820		$	138,140

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

	March 31,			December 31,
	2017			2016
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

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

	Three Months Ended
	March 31, 2017
Contractual interest expense	$	755
Amortization of debt discount		1,481
Amortization of debt issuance costs		200
Total interest expense related to the 2021 Notes	$	2,436

In connection with the offering of the 2021 Notes, the Company entered into convertible note hedge transactions with certain bank counterparties in which the Company has the option to purchase initially (subject to adjustment for certain specified events) a total of approximately 1.8 million shares of the Company’s common stock at a price of approximately $96.37 per share. The total cost of the convertible note hedge transactions was $45.1 million. In addition, the Company sold warrants to certain bank counterparties whereby the holders of the warrants have the option to purchase initially (subject to adjustment for certain specified events) a total of approximately 1.8 million shares of the Company’s common stock at a price of $127.28 per share. The Company received $33.1 million in cash proceeds from the sale of these warrants. Taken together, the purchase of the convertible note hedges and the sale of warrants are intended to offset any actual dilution from the conversion of these notes and to effectively increase the overall conversion price from $96.37 to $127.28 per share. As these transactions meet certain accounting criteria, the convertible note hedges and warrants are recorded in stockholders’ equity and are not accounted for as derivatives. The net cost of $12.0 million incurred in connection with the convertible note hedge and warrant transactions was recorded as a reduction to additional paid-in capital on the consolidated balance sheet.

Capital Royalty Term Loan

On October 24, 2014, the Company entered into a credit facility (the “credit facility”) with Capital Royalty Partners and certain of its affiliates (the “lenders”) under which, subject to certain conditions, the Company could enter into three term loan agreements totaling $50.0 million with the lenders on or before September 30, 2015. In June 2016, the Company paid the outstanding principal and repayment fees totaling $21.0 million to the lenders, and the credit facility terminated and is now no longer in effect.