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Accounting for Stock Based Compensation - Fair Value of Option on date of grant (Detail)
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Statement Of Stockholders Equity [Abstract]      
Expected volatility     33.00%
Weighted-average expected volatility     33.00%
Expected lives     3 years
Risk-free interest rate     1.49%
Risk-free interest rate     1.93%
Expected dividend yield 0.00% 0.00% 0.00%