Restructuring - Activity in Restructuring Liability Accounts (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2017 USD ($)
Restructuring Cost and Reserve [Line Items]
Beginning Balance	$ 1,960
Provision-net	565
Usage	(912)
Ending Balance	1,613
Lease/Rental Terminations [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	1,786
Provision-net	(149)
Usage	(245)
Ending Balance	1,392
One-Time Employee Termination Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	65
Provision-net	805
Usage	(649)
Ending Balance	221
Datacenter Consolidation, Other [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	109
Provision-net	(91)
Usage	$ (18)