Fair Value of Financial Instruments - Schedule of Fair Value of Assets and Financing Liability on Total Investments (Detail) - USD ($)	Dec. 31, 2021	Dec. 31, 2020
Amortized Cost (Carrying Value)
Fair Value Of Financial Instruments [Line Items]
Total cash equivalents and investments	$ 160,400
Less cash equivalents	(23,800)
Total Investments	136,600
Amortized Cost (Carrying Value) | Commercial Bonds and Paper | Fair Value, Inputs, Level 2
Fair Value Of Financial Instruments [Line Items]
Total cash equivalents and investments	115,200
Amortized Cost (Carrying Value) | Money Market Funds | Fair Value, Inputs, Level 1
Fair Value Of Financial Instruments [Line Items]
Total cash equivalents and investments	21,300
Amortized Cost (Carrying Value) | U.S. Treasuries | Fair Value, Inputs, Level 2
Fair Value Of Financial Instruments [Line Items]
Total cash equivalents and investments	23,900
Amortized Cost (Carrying Value) | U.S. Treasuries | Fair Value, Inputs, Level 2 | Cash Equivalents
Fair Value Of Financial Instruments [Line Items]
Total cash equivalents and investments		$ 59,500
Gross Unrealized Holding Losses
Fair Value Of Financial Instruments [Line Items]
Total cash equivalents and investments	300
Total Investments	300
Gross Unrealized Holding Losses | Commercial Bonds and Paper | Fair Value, Inputs, Level 2
Fair Value Of Financial Instruments [Line Items]
Total cash equivalents and investments	200
Gross Unrealized Holding Losses | U.S. Treasuries | Fair Value, Inputs, Level 2
Fair Value Of Financial Instruments [Line Items]
Total cash equivalents and investments	100
Estimated Fair Value
Fair Value Of Financial Instruments [Line Items]
Total cash equivalents and investments	160,100
Less cash equivalents	(23,800)
Total Investments	136,300
Estimated Fair Value | Commercial Bonds and Paper | Fair Value, Inputs, Level 2
Fair Value Of Financial Instruments [Line Items]
Total cash equivalents and investments	115,000.0
Estimated Fair Value | Money Market Funds | Fair Value, Inputs, Level 1
Fair Value Of Financial Instruments [Line Items]
Total cash equivalents and investments	21,300
Estimated Fair Value | U.S. Treasuries | Fair Value, Inputs, Level 2
Fair Value Of Financial Instruments [Line Items]
Total cash equivalents and investments	$ 23,800
Estimated Fair Value | U.S. Treasuries | Fair Value, Inputs, Level 2 | Cash Equivalents
Fair Value Of Financial Instruments [Line Items]
Total cash equivalents and investments		$ 59,500