Contingent Consideration (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2019	Feb. 15, 2019
Contingent Consideration [Abstract]
Fair value of contingent consideration		$ 0	$ 1,200
Contingent liability outstanding	$ 0	$ 0
Payments of the liability-classified contingent consideration arrangements	$ (1,701)

Amount of liability recognized arising from contingent consideration in a business combination, expected to be settled beyond one year or the normal operating cycle, if longer.

No definition available.

Name:	gvp_ContingentConsideration
Namespace Prefix:	gvp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant