Convertible Notes (Details 3) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Interest expense related to notes
Amortization of discount and debt issuance costs			$ 3,523	$ 3,326
Interest expense	$ 3,261	$ 3,163	6,467	6,304
Convertible Senior Notes
Interest expense related to notes
Interest expense	2,162	2,063	4,299	4,102
Convertible Senior Notes \| 1.125% Convertible Senior Notes due 2018
Interest expense related to notes
Interest	388	388	776	776
Amortization of discount and debt issuance costs	$ 1,774	$ 1,675	$ 3,523	$ 3,326
Convertible notes stated interest rate (as a percent)	1.125%		1.125%		1.125%
Debt Instrument, Interest Rate, Effective Percentage	5.50%	5.50%	5.50%	5.50%

Amount of amortization expense attributable to debt discount (premium) and debt issuance costs.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585

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Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
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-Subparagraph (SX 210.5-02.22(a)(1))
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-Name Accounting Standards Codification
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Contractual interest rate for funds borrowed, under the debt agreement.

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Amount of the cost of borrowed funds accounted for as interest expense.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391

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-Topic 942
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-Subparagraph (SX 210.9-04.9)
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Amount of the cost of borrowed funds accounted for as interest expense for debt.

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