Debt - Total Interest Expense Recognized Related to the Convertible Notes (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Debt Instrument [Line Items]
Total interest expense	$ 16,847	$ 18,309	$ 52,403	$ 55,002
Convertible Notes
Debt Instrument [Line Items]
Contractual interest expense	2,840	1,250	6,033	3,750
Amortization of debt issuance costs	348	273	944	797
Amortization of debt discount	3,264	1,920	7,909	5,602
Total interest expense	$ 6,452	$ 3,443	$ 14,886	$ 10,149

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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