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Share-Based Compensation - Additional Information (Detail)
1 Months Ended 12 Months Ended
Nov. 30, 2020
Tradingday
$ / shares
Feb. 29, 2020
Dec. 31, 2020
USD ($)
Target
shares
Dec. 31, 2019
USD ($)
shares
Dec. 31, 2018
USD ($)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Common stock, authorized shares | shares     6,000,000,000 6,000,000,000  
2017 Employee Plan [Member]          
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Shares of common stock reserved for future issuance | shares     3,588,672    
Compensation expense | $     $ 20,000,000 $ 16,000,000 $ 16,000,000
Unrecognized compensation costs related to unvested awards | $     $ 21,000,000    
Unrecognized compensation costs related to unvested awards, weighted-average period     2 years 2 months 12 days    
Total fair value of shares vested | $     $ 27,000,000 $ 21,000,000 $ 9,000,000
2017 Employee Plan [Member] | Maximum [Member]          
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Common stock, authorized shares | shares     8,000,000    
2017 Director Plan [Member]          
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Shares of common stock reserved for future issuance | shares     72,982    
2017 Director Plan [Member] | Maximum [Member]          
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Common stock, authorized shares | shares     450,000    
Performance Stock Units ("PSUs") [Member]          
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Market capitalization | $     $ 1,000,000    
Vesting rights     zero to 200    
Performance Stock Units ("PSUs") [Member] | Special Awards [Member]          
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Compensation expense | $     $ 0    
Share-based compensation arrangement by share-based payment award performance period   1 year 3 years    
Performance Stock Units ("PSUs") [Member] | Special Awards [Member] | Eight Share Price Targets [Member]          
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Vesting rights One-eighth        
Consecutive trading day period | Tradingday 20        
PSUs remaining performance period forfeited 4 years        
Share price target achieved | Target     4    
Percentage of awards granted vested     50.00%    
Performance Stock Units ("PSUs") [Member] | Special Awards [Member] | One Goal Achieved [Member]          
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Vesting rights   100      
Performance Stock Units ("PSUs") [Member] | Maximum [Member] | Annual Grants [Member]          
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Vesting rights   200      
Performance Stock Units ("PSUs") [Member] | Maximum [Member] | Special Awards [Member]          
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Vesting rights     200    
Average closing sales price per share, | $ / shares $ 25.00        
Performance Stock Units ("PSUs") [Member] | Minimum [Member] | Special Awards [Member]          
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Vesting rights   0      
Average closing sales price per share, | $ / shares $ 11.00        
Performance Stock Units ("PSUs") [Member] | Minimum [Member] | Annual Grants [Member]          
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Vesting rights     0