Goodwill and Other Intangible Assets - Components of Identifiable Intangible assets (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Goodwill and Intangible Assets [Line Items]
Total Intangible Assets, Gross Carrying Value	$ 28,429	$ 28,429
Intangible Assets, Accumulated Amortization	5,019	2,964
Total Intangible Assets, Net Carrying Value	$ 23,410	$ 25,465
Client Relationships [Member] | IT Staffing Services [Member]
Goodwill and Intangible Assets [Line Items]
Amortization Period (In Years)	12 years	12 years
Intangible Assets, Gross Carrying Value	$ 7,999	$ 7,999
Intangible Assets, Accumulated Amortization	2,194	1,694
Intangible Assets, Net Carrying Value	$ 5,805	$ 6,305
Client Relationships [Member] | Data and Analytics Services [Member]
Goodwill and Intangible Assets [Line Items]
Amortization Period (In Years)	12 years	12 years
Intangible Assets, Gross Carrying Value	$ 16,671	$ 16,671
Intangible Assets, Accumulated Amortization	1,678	636
Intangible Assets, Net Carrying Value	$ 14,993	$ 16,035
Covenant Not-to-Compete [Member] | IT Staffing Services [Member]
Goodwill and Intangible Assets [Line Items]
Amortization Period (In Years)	5 years	5 years
Intangible Assets, Gross Carrying Value	$ 319	$ 319
Intangible Assets, Accumulated Amortization	210	162
Intangible Assets, Net Carrying Value	$ 109	$ 157
Covenant Not-to-Compete [Member] | Data and Analytics Services [Member]
Goodwill and Intangible Assets [Line Items]
Amortization Period (In Years)	5 years	5 years
Intangible Assets, Gross Carrying Value	$ 761	$ 761
Intangible Assets, Accumulated Amortization	184	70
Intangible Assets, Net Carrying Value	$ 577	$ 691
Trade Name [Member] | IT Staffing Services [Member]
Goodwill and Intangible Assets [Line Items]
Amortization Period (In Years)	3 years	3 years
Intangible Assets, Gross Carrying Value	$ 249	$ 249
Intangible Assets, Accumulated Amortization	$ 249	211
Intangible Assets, Net Carrying Value		$ 38
Trade Name [Member] | Data and Analytics Services [Member]
Goodwill and Intangible Assets [Line Items]
Amortization Period (In Years)	5 years	5 years
Intangible Assets, Gross Carrying Value	$ 1,221	$ 1,221
Intangible Assets, Accumulated Amortization	295	112
Intangible Assets, Net Carrying Value	$ 926	$ 1,109
Technology [Member] | Data and Analytics Services [Member]
Goodwill and Intangible Assets [Line Items]
Amortization Period (In Years)	7 years	7 years
Intangible Assets, Gross Carrying Value	$ 1,209	$ 1,209
Intangible Assets, Accumulated Amortization	209	79
Intangible Assets, Net Carrying Value	$ 1,000	$ 1,130