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Recent Accounting Pronouncements - Additional Information (Detail) - ASU 2016-09 [Member] - USD ($)
3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2017
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]    
Recognition of an excess tax benefit and deficiency   $ 1,100,000
Decrease in effective tax rate due to recognition of an excess tax benefit and deficiency 0.60%  
Increase in effective tax rate due to recognition of an excess tax benefit and deficiency   4.60%
Maximum [Member]    
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]    
Recognition of an excess tax benefit and deficiency $ 100,000