Annual report pursuant to Section 13 and 15(d)

Property and Equipment - Additional Information (Detail)

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Property and Equipment - Additional Information (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Property Plant And Equipment [Abstract]      
Interest capitalized in conjunction with construction projects and software development $ 2.2 $ 2.8 $ 1.9
Commitments for facility construction projects $ 31.9