Fair Value of Financial Instruments - Additional Information (Detail) - USD ($) $ in Thousands |
12 Months Ended | ||
---|---|---|---|
Dec. 31, 2019 |
Dec. 31, 2018 |
Mar. 31, 2018 |
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||
Unrealized gain (loss) on investments | $ 6,600 | ||
Long-term investments | 132,188 | $ 0 | |
Level 2 | |||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||
Long-term investments | $ 0 | $ 0 | |
Convertible Senior Notes Due 2023 | |||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||
Debt instrument, interest rate | 0.00% | ||
Convertible Senior Notes Due 2023 | Level 2 | |||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||
Debt instrument, interest rate | 0.00% | ||
Estimated fair value of convertible senior notes | $ 929,200 |