Debt (Tables)

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

Schedule of Convertible Notes

Our Notes are summarized as follows (in thousands): 

	As of December 31,
	2018
2023 Notes
Principal amount	$	150,000
Debt discount, net of amortization	(27,653		)
Debt issuance costs, net of amortization	(3,659		)
Liability component	$	118,688
Equity component	$	28,045
Less: debt issuance costs allocated to equity	(853		)
Tax effects	(6,619		)
Equity component, net	$	20,573

	As of December 31,
	2018			2017
2019 Notes
Principal amount	$	345,000		$	345,000
Debt discount, net of amortization	(9,366		)	(23,178		)
Debt issuance costs, net of amortization	(1,360		)	(2,865		)
Liability component	$	334,274		$	318,957
Equity component	$	63,643		$	63,643
Less: debt issuance costs allocated to equity	(1,582		)	(1,582		)
Greenshoe option value	568			568
Tax effects	485			485
Equity component, net	$	63,114		$	63,114

Schedule of Interest Expense

Interest expense recognized related to the Notes was as follows (in thousands):

	Year Ended December 31,
2023 Notes	2018
2.25% Coupon	$	281
Amortization of debt issuance costs	52
Amortization of debt discount	392
Interest expense on 2023 Notes	$	725

	Year Ended December 31,
2019 Notes	2018		2017		2016
0.75% coupon	$	2,595	$	2,580	$	2,588
Amortization of debt issuance costs	1,505		1,536		1,350
Amortization of debt discount	13,812		12,937		12,400
Interest expense on 2019 Notes	$	17,912	$	17,053	$	16,338