Debt - Total Interest Expense Recognized Related to the Convertible Notes (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Debt Instrument [Line Items]
Total interest expense	$ 17,256	$ 18,250	$ 35,556	$ 36,693
Convertible Notes
Debt Instrument [Line Items]
Contractual interest expense	1,943	1,250	3,193	2,500
Amortization of debt issuance costs	321	265	596	524
Amortization of debt discount	2,716	1,867	4,644	3,682
Total interest expense	$ 4,980	$ 3,382	$ 8,433	$ 6,706

Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 45
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Amount of amortization expense attributable to debt issuance costs.

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

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Represents the portion of interest incurred in the period on debt arrangements that was charged against earnings, excluding amortization of debt discount (premium) and financing costs.

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