Fair Value Measurements - Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Assets
Assets	$ 336,528	$ 363,151
Level 1
Assets
Assets	54,841	17,664
Level 2
Assets
Assets	281,687	345,487
Level 3
Assets
Assets	0	0
Cash Equivalents | Money Market Funds
Assets
Assets	54,841	17,664
Cash Equivalents | Corporate Commercial Paper
Assets
Assets		6,983
Cash Equivalents | Corporate Debt Securities
Assets
Assets		10,204
Cash Equivalents | Level 1 | Money Market Funds
Assets
Assets	54,841	17,664
Cash Equivalents | Level 1 | Corporate Commercial Paper
Assets
Assets		0
Cash Equivalents | Level 1 | Corporate Debt Securities
Assets
Assets		0
Cash Equivalents | Level 2 | Money Market Funds
Assets
Assets	0	0
Cash Equivalents | Level 2 | Corporate Commercial Paper
Assets
Assets		6,983
Cash Equivalents | Level 2 | Corporate Debt Securities
Assets
Assets		10,204
Cash Equivalents | Level 3 | Money Market Funds
Assets
Assets	0	0
Cash Equivalents | Level 3 | Corporate Commercial Paper
Assets
Assets		0
Cash Equivalents | Level 3 | Corporate Debt Securities
Assets
Assets		0
Short-term marketable securities | Corporate Commercial Paper
Assets
Assets	93,347	95,088
Short-term marketable securities | Corporate Debt Securities
Assets
Assets	142,640	154,690
Short-term marketable securities | Government- sponsored Enterprise Securities
Assets
Assets	16,055	26,265
Short-term marketable securities | Level 1 | Corporate Commercial Paper
Assets
Assets	0	0
Short-term marketable securities | Level 1 | Corporate Debt Securities
Assets
Assets	0	0
Short-term marketable securities | Level 1 | Government- sponsored Enterprise Securities
Assets
Assets	0	0
Short-term marketable securities | Level 2 | Corporate Commercial Paper
Assets
Assets	93,347	95,088
Short-term marketable securities | Level 2 | Corporate Debt Securities
Assets
Assets	142,640	154,690
Short-term marketable securities | Level 2 | Government- sponsored Enterprise Securities
Assets
Assets	16,055	26,265
Short-term marketable securities | Level 3 | Corporate Commercial Paper
Assets
Assets	0	0
Short-term marketable securities | Level 3 | Corporate Debt Securities
Assets
Assets	0	0
Short-term marketable securities | Level 3 | Government- sponsored Enterprise Securities
Assets
Assets	0	0
Long-term marketable securities | Corporate Debt Securities
Assets
Assets	8,534	14,202
Long-term marketable securities | Government- sponsored Enterprise Securities
Assets
Assets	21,111	38,055
Long-term marketable securities | Level 1 | Corporate Debt Securities
Assets
Assets	0	0
Long-term marketable securities | Level 1 | Government- sponsored Enterprise Securities
Assets
Assets	0	0
Long-term marketable securities | Level 2 | Corporate Debt Securities
Assets
Assets	8,534	14,202
Long-term marketable securities | Level 2 | Government- sponsored Enterprise Securities
Assets
Assets	21,111	38,055
Long-term marketable securities | Level 3 | Corporate Debt Securities
Assets
Assets	0	0
Long-term marketable securities | Level 3 | Government- sponsored Enterprise Securities
Assets
Assets	$ 0	$ 0