Investments and Fair Value Measurements - Schedule of Financial Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Fair Value Assets Measured on Recurring and Nonrecurring Basis [line items]
Cash equivalents	$ 624,481	$ 582,753
Total	896,178	1,147,771
Level 1
Fair Value Assets Measured on Recurring and Nonrecurring Basis [line items]
Cash equivalents	624,481	582,753
Total	629,681	587,829
Level 2
Fair Value Assets Measured on Recurring and Nonrecurring Basis [line items]
Cash equivalents	0	0
Total	266,497	559,942
Level 3
Fair Value Assets Measured on Recurring and Nonrecurring Basis [line items]
Cash equivalents	0	0
Total	0	0
Investment securities
Fair Value Assets Measured on Recurring and Nonrecurring Basis [line items]
Short-term investments	266,497	404,252
Long-term		155,690
Investment securities | Level 1
Fair Value Assets Measured on Recurring and Nonrecurring Basis [line items]
Short-term investments	0	0
Long-term		0
Investment securities | Level 2
Fair Value Assets Measured on Recurring and Nonrecurring Basis [line items]
Short-term investments	266,497	404,252
Long-term		155,690
Investment securities | Level 3
Fair Value Assets Measured on Recurring and Nonrecurring Basis [line items]
Short-term investments	0	0
Long-term		0
Certificate of deposit
Fair Value Assets Measured on Recurring and Nonrecurring Basis [line items]
Other non-current assets	5,200	5,076
Certificate of deposit | Level 1
Fair Value Assets Measured on Recurring and Nonrecurring Basis [line items]
Other non-current assets	5,200	5,076
Certificate of deposit | Level 2
Fair Value Assets Measured on Recurring and Nonrecurring Basis [line items]
Other non-current assets	0	0
Certificate of deposit | Level 3
Fair Value Assets Measured on Recurring and Nonrecurring Basis [line items]
Other non-current assets	0	0
Cash
Fair Value Assets Measured on Recurring and Nonrecurring Basis [line items]
Cash equivalents	85,816	308,521
Cash | Level 1
Fair Value Assets Measured on Recurring and Nonrecurring Basis [line items]
Cash equivalents	85,816	308,521
Cash | Level 2
Fair Value Assets Measured on Recurring and Nonrecurring Basis [line items]
Cash equivalents	0	0
Cash | Level 3
Fair Value Assets Measured on Recurring and Nonrecurring Basis [line items]
Cash equivalents	0	0
Cash equivalents
Fair Value Assets Measured on Recurring and Nonrecurring Basis [line items]
Cash equivalents	538,665	274,232
Cash equivalents | Level 1
Fair Value Assets Measured on Recurring and Nonrecurring Basis [line items]
Cash equivalents	538,665	274,232
Cash equivalents | Level 2
Fair Value Assets Measured on Recurring and Nonrecurring Basis [line items]
Cash equivalents	0	0
Cash equivalents | Level 3
Fair Value Assets Measured on Recurring and Nonrecurring Basis [line items]
Cash equivalents	$ 0	$ 0