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Stockholders' Equity - Summary of Assumptions Used to Calculate the Grant Date Fair Value Based on Total Shareholder Return (Detail) - $ / shares
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Number of units granted 20,587 71,893 101,062
PSUs – Total Shareholder Return [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Number of units granted 124,755 65,796 129,150
Weighted average fair value on grant date $ 57.14 $ 59.91 $ 43.13
Expected Price volatility 26.50% 29.90% 32.90%
Risk-free interest rate 0.98% 1.05% 0.63%