Borrowings - Interest Expense of Debt (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Debt Instrument [Line Items]
Amortization of debt discount on Notes			$ 1,289	$ 1,218
3.50% Convertible Senior Notes due October 1, 2024 \| Notes
Debt Instrument [Line Items]
Interest expense on Notes	$ 1,313	$ 1,269	2,625	2,581
Amortization of debt discount on Notes	$ 654	$ 618	$ 1,289	$ 1,218

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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
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-Section 45
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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