Property and Equipment, net - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Owned Assets:
Owned assets, gross	$ 211,572	$ 207,318
Less: Accumulated depreciation and amortization	(144,285)	(141,059)
Owned assets, net	67,287	66,259
Assets under capital leases:
Capital leased assets, gross	1,269	1,818
Less: Accumulated depreciation and amortization	(881)	(1,320)
Assets under capital leases, net	388	498
Property and equipment, net	67,675	66,757
Network equipment and computers
Owned Assets:
Owned assets, gross	78,693	77,587
Software
Owned Assets:
Owned assets, gross	63,668	59,325
Leasehold improvements
Owned Assets:
Owned assets, gross	37,079	38,857
Assets under capital leases:
Capital leased assets, gross	712	941
Office furniture and equipment
Owned Assets:
Owned assets, gross	19,354	19,667
Assets under capital leases:
Capital leased assets, gross	7	167
Motor vehicles
Owned Assets:
Owned assets, gross	556	638
Assets under capital leases:
Capital leased assets, gross	$ 550	710
Buildings
Owned Assets:
Estimated useful lives	30 years
Owned assets, gross	$ 1,097	1,245
Land
Owned Assets:
Owned assets, gross	718	815
Capital work in progress
Owned Assets:
Owned assets, gross	$ 10,407	$ 9,184
Minimum | Network equipment and computers
Owned Assets:
Estimated useful lives	3 years
Minimum | Software
Owned Assets:
Estimated useful lives	3 years
Minimum | Leasehold improvements
Owned Assets:
Estimated useful lives	3 years
Minimum | Office furniture and equipment
Owned Assets:
Estimated useful lives	3 years
Minimum | Motor vehicles
Owned Assets:
Estimated useful lives	2 years
Maximum | Network equipment and computers
Owned Assets:
Estimated useful lives	5 years
Maximum | Software
Owned Assets:
Estimated useful lives	5 years
Maximum | Leasehold improvements
Owned Assets:
Estimated useful lives	8 years
Maximum | Office furniture and equipment
Owned Assets:
Estimated useful lives	8 years
Maximum | Motor vehicles
Owned Assets:
Estimated useful lives	5 years