Long-Term Obligations (in thousands, except percentages):



	As of March 31, 2015			As of December 31, 2014
5.00% Convertible Senior Notes due October 2017, interest payable semi-annually in April and October	$	130,000		$	130,000
Bank Loans due May 2015, principal and interest payable monthly, weighted-average effective interest rates of 5.5% and 5.5%, net of unamortized discounts of $2 and $8 at March 31, 2105 and December 31, 2014, respectively	1,912			3,722
Obligation for building and improvements, effective interest rate of 4.9%, expiring October 2026	5,801			5,868
Capital lease liabilities, expiring January 2016, net of unamortized discounts of $10 and $17 at March 31, 2015 and December 31, 2014, respectively	124			156
Total long-term obligations	137,837			139,746
Less current portion	(2,313		)	(4,144		)
Non-current portion	$	135,524		$	135,602

Convertible Senior Notes

On September 17, 2012, the Company issued $130 million aggregate principal amount of Convertible Senior Notes (the "Notes") in a private offering to qualified institutional buyers in reliance on Rule 144A under the Securities Act of 1933, as amended. The Notes bear interest at a fixed rate of 5.00% per year, payable semiannually in arrears on April 1 and October 1 of each year. The Notes mature on October 1, 2017, unless earlier converted, redeemed, or repurchased. The Notes are convertible at any time prior to the third trading day immediately preceding the maturity date, at the option of the holders, into shares of common stock.

The net proceeds received were $124.7 million after deducting underwriting discounts and commissions and other offering costs of $5.3 million. The debt issuance costs are recorded in other assets and are amortized to interest expense, using the effective interest method, over the five-year term of the Notes. At March 31, 2015 and December 31, 2014, unamortized deferred debt issuance costs totaled $2.8 million and $3.1 million, respectively.

The Notes are initially convertible into a total of 28.1 million shares of common stock, which is equal to an initial conversion rate of 216.0644 shares of common stock per $1,000 principal amount of the Notes (equivalent to an initial conversion price of approximately $4.63 per share of common stock), and will be subject to adjustment upon the occurrence of certain events. The maximum conversion rate is 275.4821 shares of common stock per $1,000 principal amount of the Notes, which would result in a maximum issuance of 35.8 million shares of common stock if all holders converted at the maximum conversion rate. In addition, under certain circumstances the Company, in connection with a make-whole fundamental change (as defined in the indenture governing the Notes), may be required to increase the conversion rate for holders of the Notes. As of March 31, 2015, no change to the conversion rate has occurred on the Notes.

The Company may not redeem the Notes prior to October 1, 2015. On or after October 1, 2015, the Company may redeem for cash all, but not less than all, of the Notes if the last reported sale price of the common stock equals or exceeds 140% of the applicable conversion price for at least 20 trading days during the 30 consecutive trading day period ending on the trading day immediately prior to the date on which the notice of the redemption is delivered. The redemption price will equal 100% of the principal amount of the Notes to be redeemed, plus any accrued and unpaid interest to, but excluding, the redemption date. In addition, if the Notes are called for redemption, a make-whole fundamental change will be deemed to occur. As a result, in certain circumstances, this would increase the conversion rate for holders who convert their Notes after a notice of redemption is delivered and on or prior to the close of business on the third business day immediately preceding the relevant redemption date. Upon a fundamental change, subject to certain exceptions, the holders may require that the Company repurchase some or all of their Notes for cash at a repurchase price equal to 100% of the principal amount of the Notes being repurchased, plus any accrued and unpaid interest to, but excluding, the fundamental change repurchase date.

On September 17, 2012, the Company entered into an indenture with Wells Fargo Bank, National Association, as trustee, relating to the Notes. The Notes are senior, unsecured obligations and rank equal in right of payment with existing and future senior, unsecured indebtedness, and will be senior in right of payment to any future indebtedness that is expressly subordinated to the Notes. The Notes will be effectively subordinated to existing and future secured indebtedness to the extent of the assets securing such indebtedness and will be structurally subordinated to all indebtedness and other liabilities and commitments of subsidiaries, including trade payables and any guarantees that they may provide with respect to any existing or future indebtedness.

Bank Loans

In May 2011, the Company entered into a Loan and Security Agreement, or the Loan Agreement, with Silicon Valley Bank, or SVB, that allowed for term loans of up to $20.0 million to be borrowed through August 31, 2012, revolving cash borrowings of up to $10.0 million, as well as letters of credit all under a secured credit facility. All borrowings under the Loan Agreement are secured by substantially all of the Company's assets, except for intellectual property, and are subject to certain other exceptions. The Loan Agreement includes limitations on the ability, among other things, to incur debt, to grant liens, to make certain investments, to make certain restricted payments such as dividend payments, and to dispose of assets, as well as requirements to meet a number of affirmative and negative covenants.

The Company borrowed under the term loans $5.0 million and $15.0 million during the years ended December 31, 2012 and 2011, respectively. Under the Loan Agreement, the term loans bear interest at the rate fixed on the date of funding equal to the U.S. treasury rate plus 3.25% per annum. The term loan borrowings are being repaid in 33 equal installments of principal, plus accrued interest which commenced on September 1, 2012. The term loans requires a final payment of 3.5% of all advances made under the term loans, in addition to principal repayments and was made on the loan maturity date, which was May 1, 2015, this was being amortized as interest expense over the term of the loan.

At March 31, 2015, the Company was in compliance with all covenants under the Loan Agreement. These include a minimum liquidity covenant requiring the Company to maintain with SVB unrestricted cash and marketable securities plus available amounts equal to or greater than the sum of all indebtedness owed to SVB plus operating liquidity.

Obligation for Building and Improvements

In November 2011, the Company entered into a lease agreement for a building in Raleigh-Durham, North Carolina, that is accounted for as a financing lease. The term of the lease and the obligation was initially 15 years through October 2026, including two 2-year extensions of the lease. Rent payments under the lease are allocated primarily between interest expense and a reduction to the long-term obligation. In the event the lease is terminated prior to the end of the 15-year period, any gain representing the amount by which the balance of the obligation exceeds the net book value of the related building and improvements would be recognized.