Borrowings - Balances of Liability and Equity Components (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
Liability component—principal amount	$ 672,855	$ 672,855
Unamortized debt discount	(27,264)	(30,308)
Liability component—net carrying amount	645,591	642,547
Equity component	$ 83,127	$ 83,127

Including the current and noncurrent portions, carrying value as of the balance sheet date of a written promise to pay a note, initially due after one year or beyond the operating cycle if longer, which can be exchanged for a specified amount of one or more securities (typically common stock), at the option of the issuer or the holder.

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