Summary of Significant Accounting Policies - Additional Information (Detail)
3 Months Ended 12 Months Ended
Mar. 31, 2021
USD ($)
shares
Mar. 31, 2021
USD ($)
Number
shares
Mar. 31, 2020
USD ($)
Number
Mar. 31, 2019
USD ($)
Number
Mar. 31, 2018
USD ($)
Summary Of Significant Accounting Policies [Line Items]          
Concentration risk percentage   100.00% 100.00% 100.00%  
Total restricted cash $ 8,400,000 $ 8,400,000 $ 8,400,000    
Inventory valuation reserves 0 0 0    
Impairment losses of deferred cost of revenue   0 1,300,000 $ 6,500,000  
Reduction of deferred cost of revenue     400,000 2,200,000  
Customer refund liability     900,000 4,300,000  
Internal-use software software, capitalized during the period   4,000,000 6,000,000 500,000  
internal-use software Software, capitalized during the period   500,000 700,000 0  
Impairment of long-lived assets   0 33,213,000 0  
Breakage revenue from unreturned kits   243,920,000 305,463,000 440,900,000  
Advertising costs   $ 11,200,000 62,600,000 $ 136,800,000  
Deferred advertising costs     $ 2,500,000    
Consumer Services [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Concentration risk percentage   81.00% 89.00% 96.00%  
Breakage revenue from unreturned kits   $ 197,525,000 $ 271,639,000 $ 425,534,000  
Deferred revenue 39,300,000 39,300,000 38,800,000 74,100,000 $ 103,900,000
Deferred revenue recognized   $ 34,400,000 $ 59,900,000 $ 99,900,000  
Research Services [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Concentration risk percentage   19.00% 9.00% 3.00%  
Breakage revenue from unreturned kits   $ 46,341,000 $ 28,268,000 $ 12,385,000  
Deferred revenue 31,900,000 31,900,000 48,600,000 48,700,000 $ 3,400,000
Deferred revenue recognized   42,800,000 28,700,000 1,900,000  
Deferred revenue related parties 30,100,000 30,100,000 45,100,000 $ 0  
Deferred revenue recognized related parties   39,900,000 26,700,000    
Transaction price allocated to remaining performance obligations $ 61,900,000 $ 61,900,000 108,300,000    
Research Services [Member] | Maximum [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Revenue, remaining performance obligation, expected timing of satisfaction, period       3 years  
Research Services [Member] | Minimum [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Revenue, remaining performance obligation, expected timing of satisfaction, period 1 year 1 year      
PGS Contracts [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Capitalized contract cost, net $ 3,300,000 $ 3,300,000 3,900,000 $ 9,900,000  
Capitalized contract cost, amortization period 1 year 1 year      
Transferred over Time [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Breakage revenue from unreturned kits   $ 24,100,000 38,000,000 57,000,000  
Consumer And Research Services [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Breakage revenue from unreturned kits   243,866,000 299,907,000 437,919,000  
Therapeutics [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Breakage revenue from unreturned kits   $ 54,000 $ 5,556,000 $ 2,981,000  
Series F-1 Redeemable Convertible Preferred Stock [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Temporary equity shares outstanding | shares 17,291,066 17,291,066      
Fair value of preferred stock $ 272,700,000 $ 272,700,000      
Series F-1 Redeemable Convertible Preferred Stock [Member] | Consumer And Research Services [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Fair value measurement input 16 16      
Series F-1 Redeemable Convertible Preferred Stock [Member] | Therapeutics [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Fair value measurement input 20 20      
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Fair value of the asset group $ 21,500,000 $ 21,500,000      
Supplier Concentration Risk [Member] | Cost Of Goods Microwaves [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Concentration risk percentage   100.00% 100.00% 100.00%  
Supplier Concentration Risk [Member] | Cost Of Goods Kits [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Concentration risk percentage   100.00% 100.00% 100.00%  
Supplier Concentration Risk [Member] | Cost Of Goods Processing Of Customer Samples [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Concentration risk percentage   100.00% 100.00% 100.00%  
Supplier Concentration Risk [Member] | Cost Of Services Processing Of Customer Samples [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Number of major laboratory service provider | Number   1 1 1  
Covid 19 [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Impairment loss on operating lease right of use asset $ 12,600,000