DEBT (Tables)

6 Months Ended

Jun. 30, 2016

Debt

Schedule of principal amount of the Senior Notes is repayable

The principal amount of the Senior Notes is repayable as follows (amounts in thousands):

April 2, 2018	$	57,500
April 2, 2019		115,000
April 2, 2020		115,000
April 2, 2021		143,750
April 2, 2022		43,750
	$	475,000

Summary of the carrying value of the Senior Notes

The following is a summary of the carrying value of the Senior Notes as of June 30, 2016 and December 31, 2015 (in thousands):

	June 30,		December 31,
	2016		2015
Principal amount of the Senior Notes	$	475,000	$	575,000
Unamortized debt discount balance		(9,739)		(11,527)
Unamortized debt issuance costs		(389)		(461)
Principal amount of the Senior Notes - long-term	$	464,872	$	563,012

Summary of the liability component of the Convertible Notes

The following is a summary of the liability component of the Convertible Notes as of June 30, 2016 and December 31, 2015 (in thousands):

	June 30,		December 31,
	2016		2015
Principal amount of the Convertible Notes	$	345,000	$	345,000
Unamortized discount of the liability component		(94,931)		(101,965)
Unamortized debt issuance costs		(5,213)		(5,722)
Principal amount of the Convertible Notes - long-term	$	244,856	$	237,313

Senior Notes

Debt

Summary of interest expense for the Notes

The following is a summary of interest expense for the three and six months ended June 30, 2016 and June 30, 2015 (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2016		2015		2016		2015
Contractual interest expense	$	12,997	$	15,281	$	28,622	$	15,281
Amortization of debt discount and debt issuance costs		564		471		1,082		471
Total interest expense	$	13,561	$	15,752	$	29,704	$	15,752

Convertible Notes

Debt

Summary of interest expense for the Notes

The following is a summary of interest expense for the three and six months ended June 30, 2016 (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2016		2015		2016		2015
Stated coupon interest	$	2,156	$	2,156	$	4,312	$	4,312
Amortization of debt discount and debt issuance costs		3,824		3,513		7,542		6,934
Total interest expense	$	5,980	$	5,669	$	11,854	$	11,246