Restructuring - Activity in Restructuring Liability Accounts (Detail) - 2013 Restructuring [Member] $ in Thousands	6 Months Ended
	Jun. 30, 2017 USD ($)
Restructuring Cost and Reserve [Line Items]
Beginning Balance	$ 1,960
Provision-net	709
Usage	(760)
Ending Balance	1,909
Lease/Rental Terminations [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	1,786
Provision-net	(3)
Usage	(170)
Ending Balance	1,613
One-Time Employee Termination Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	65
Provision-net	805
Usage	(574)
Ending Balance	296
Datacenter Consolidation, Other [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	109
Provision-net	(93)
Usage	$ (16)