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Fair Value Measurements - Additional Information (Detail) - USD ($)
9 Months Ended
Sep. 30, 2017
Dec. 31, 2016
Fair Value Disclosures [Abstract]    
Assets at fair value on recurring basis $ 0 $ 0
Liabilities at fair value on recurring basis 0 $ 0
Fair value of assets transfers in or out, level 1 to level 2 0  
Fair value of assets transfers in or out, level 2 to level 1 0  
Fair value, asset transfers into Level 3 0  
Fair value, asset transfers out of Level 3 $ 0