Debt (Tables)

9 Months Ended

Sep. 30, 2017

Debt Disclosure [Abstract]

Summary of convertible notes

The Convertible Notes consist of the following:

Liability component	September 30, 2017			December 31, 2016
Principal	$	150,000		$	150,000
Less: Debt issuance costs	(2,208		)	(2,457		)
Less: Debt discount, net(1)	(44,329		)	(49,327		)
Net carrying amount	$	103,463		$	98,216

(1) Included in the consolidated balance sheets within convertible senior notes (due 2022) and amortized to interest expense over the remaining life of the Convertible Notes using the effective interest rate method.

Summary of interest expense recognized related to the Convertible Notes

The following table sets forth total interest expense recognized related to the Convertible Notes:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2017			2016			2017			2016
Contractual interest expense	$	1,134		$	1,131		$	3,375		$	3,372
Amortization of debt issuance costs	86			77			249			224
Amortization of debt discount	1,725			1,546			4,999			4,487
Total	$	2,945		$	2,754		$	8,623		$	8,083
Effective interest rate of the liability component	11		%	11		%	11		%	11		%