Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)		9 Months Ended
	Jan. 01, 2019	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Significant Accounting Policies [Line Items]
Operating lease, right-of-use asset	$ 27,500,000		$ 24,779,000	$ 26,385,000
Operating lease, liability, current			2,829,000	2,571,000
Operating lease, liability, noncurrent			$ 26,047,000	$ 28,170,000
Accounting Standard Update (ASU) No. 2016-02 [Member]
Significant Accounting Policies [Line Items]
Operating lease, right-of-use asset	27,500,000
Operating lease, liability, current	2,900,000
Operating lease, liability, noncurrent	29,200,000
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]			true
Accounting Standard Update (ASU) No. 2016-02 [Member] | Deferred Rent [Member]
Significant Accounting Policies [Line Items]
Operating lease, expense	4,900,000
Accounting Standard Update (ASU) No. 2016-02 [Member] | Prepaid Rent [Member]
Significant Accounting Policies [Line Items]
Operating lease, expense	$ 300,000
ASU No. 2017-04 [Member]
Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]			true
Change in Accounting Principle, Accounting Standards Update, Adoption Date			Jan. 01, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]			true
ASU No. 2018-15 [Member]
Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]			true
Change in Accounting Principle, Accounting Standards Update, Adoption Date			Jan. 01, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]			true
ASU 2016-13 [Member]
Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]			true
Change in Accounting Principle, Accounting Standards Update, Adoption Date			Jan. 01, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]			true
ASU No. 2018-13 [Member]
Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]			true
Change in Accounting Principle, Accounting Standards Update, Adoption Date			Jan. 01, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]			true
Coronavirus, Aid, Relief and Economic Security Act (CARES Act) [Member] | Forecast [Member]
Significant Accounting Policies [Line Items]
Percentage of deferred employee share of FICA taxes		6.20%
Deferred payroll tax payment		$ 137,700