DEBT (Tables)

3 Months Ended

Mar. 31, 2017

Debt Disclosure [Abstract]

Summary of Convertible Debt

Convertible Notes

The following table summarizes information regarding the Company’s convertible debt:

	March 31, 2017			December 31, 2016
Convertible Notes due in 2017	$	22,497		$	22,503
Unamortized deferred offering costs		(2	)		(25	)
Convertible Notes due in 2017, net		22,495			22,478
Convertible Notes due in 2018		374,980			374,980
Unamortized discount		(23,867	)		(27,566	)
Unamortized deferred offering costs		(3,000	)		(3,484	)
Convertible Notes due in 2018, net		348,113			343,930
Convertible Notes due in 2020		374,993			374,993
Unamortized discount		(50,069	)		(53,239	)
Unamortized deferred offering costs		(4,600	)		(4,923	)
Convertible Notes due in 2020, net		320,324			316,831
Total convertible debt, net	$	690,932		$	683,239
Fair value of fixed rate convertible debt
Convertible Notes due in 2017 (1)	$	96,433		$	90,977
Convertible Notes due in 2018 (1)		426,424			423,202
Convertible Notes due in 2020 (1)		442,289			442,754
Total	$	965,146		$	956,933

(1) The fair value of the Company’s fixed rate convertible debt is based on open market trades and is classified as Level 1 in the fair value hierarchy.

Summary of Interest Expense on Debt

Interest expense on the Company’s convertible debt consisted of the following:

	Three Months Ended March 31,
	2017		2016
Coupon interest	$	2,364	$	2,506
Amortization of issuance costs		886		825
Accretion of debt discount		6,869		6,512
Total interest expense on convertible debt	$	10,119	$	9,843