XML 73 R57.htm IDEA: XBRL DOCUMENT v3.20.4
Income Taxes - Summary of Effective Tax Rate Differed from U.S. Statutory Federal Tax Rate (Detail)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Income Tax Disclosure [Abstract]      
Statutory federal tax rate 21.00% 21.00% 21.00%
State taxes, net of federal benefit 3.20% 6.20% 0.30%
Adjustment for final positions on filed returns 0.60% (0.20%) (1.10%)
Nondeductible expenses and other, net 0.70% 1.30% 1.20%
Federal and state tax credits (4.90%) (7.50%) (6.40%)
Other, net 0.10% 0.20%  
Total 20.70% 21.00% 15.00%