Long-term debt: (Tables)

12 Months Ended

Dec. 31, 2013

Long-term debt:

Schedule of debt and equity components for the Convertible Notes

The debt and equity components for the Convertible Notes were as follows (in thousands):

	December 31,
	2013			2012
Principal amount of convertible senior notes	$	91,978		$	91,978
Unamortized discount		(3,099	)		(9,494	)
Net carrying amount		88,879			82,484
Additional paid-in capital		74,933			74,933

Schedule of interest expense recognized and the effective interest rate for the Convertible Notes

The amount of interest expense recognized and effective interest rate for the years ended December 31, 2013, 2012 and 2011 were as follows (in thousands):

	Year Ended December 31,
	2013			2012			2011
Contractual coupon interest	$	920		$	920		$	920
Amortization of discount and costs		6,409			5,886			5,405
Interest expense	$	7,329		$	6,806		$	6,325
Effective interest rate		8.7	%		8.7	%		8.7	%

Schedule of aggregate future contractual maturities of long-term debt

 The aggregate future contractual maturities of long-term debt were as follows as of December 31, 2013 (in thousands):

For the year ending December 31,
2014	$	—
2015		—
2016		—
2017		—
2018		240,000
Thereafter(1)		91,978
Total	$	331,978

(1)

The Convertible Notes mature in June 2027. Holders of the $92.0 million of Convertible Notes have the right to require the Company to repurchase for cash all or some of their notes on June 15, 2014, 2017 and 2022 at a redemption price of 100% of the principal amount plus accrued interest.