Fair Value Measurements - Recurring (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Fair Value
Short-term investments	$ 2,530	$ 53,245
Equity securities without readily determinable fair values	10,852	5,000
Fair Value, Assets, Level 1 to Level 2 Transfers, Amount	0	0
Fair Value, Assets, Level 2 to Level 1 Transfers, Amount	0	0
Fair Value, Liabilities, Level 1 to Level 2 Transfers, Amount	0
Fair value assets level 3 net transfers	0	0
Fair value liabilities level 3 net transfers	0	0
Recurring
Fair Value
Cash and cash equivalents	720,104	733,324
Short-term investments	2,530	53,245
Equity securities without readily determinable fair values	10,852	5,000
Contingent liability	4,138	4,514
Level 1 | Recurring
Fair Value
Cash and cash equivalents	720,104	733,324
Short-term investments	0	0
Equity securities without readily determinable fair values	0	0
Contingent liability	0	0
Level 2 | Recurring
Fair Value
Cash and cash equivalents	0	0
Short-term investments	2,530	53,245
Equity securities without readily determinable fair values	10,852	5,000
Contingent liability	0	0
Level 3 | Recurring
Fair Value
Cash and cash equivalents	0	0
Short-term investments	0	0
Equity securities without readily determinable fair values	0	0
Contingent liability	$ 4,138	$ 4,514