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Stock-Based Awards - Summary of Share Based Payment Awards Other Than OptionsValuation Assumptions (Detail) - Performance Based Restricted Stock Unit [Member]
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Schedule Of Share Based Payment Awards Other Than OptionsValuation Assumptions [Line Items]    
Historical stock price volatility (low) 21.00% 22.00%
Historical stock price volatility (high) 36.00% 42.00%
Historical stock price volatility (average) 26.00% 28.00%
Risk free interest rate 1.47% 2.56%
Expected dividend yield 0.00% 0.00%