Goodwill and Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Other net intangibles	$ 5,575	$ 8,378
Weighted average amortization period of intangible assets	3 years 4 months 24 days	4 years 4 months 24 days	5 years 4 months 24 days
Amortization expense of intangible assets	$ 2,800	$ 3,400	$ 899
Amortization from capitalized software development costs	7	$ 188	$ 191
Classic Consulting [Member]
Finite-Lived Intangible Assets [Line Items]
Impairment charges of cumulative goodwill	$ 54,600