Acquisitions - Summary of Estimated Acquisition Date Fair Values of Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Jul. 31, 2015	Jul. 02, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Goodwill	$ 195,733			$ 193,831	$ 199,802
EMEA [Member]
Business Acquisition [Line Items]
Goodwill	$ 9,684
Qelp [Member]
Business Acquisition [Line Items]
Goodwill		$ 9,900
Purchase price, total		$ 15,600
Qelp [Member] | EMEA [Member]
Business Acquisition [Line Items]
Cash and cash equivalents			$ 450
Receivables			1,471
Prepaid expenses			24
Total current assets			1,945
Property and equipment			2,168
Goodwill			10,054
Intangibles			6,000
Deferred charges and other assets			55
Short-term debt			(323)
Accrued employee compensation and benefits			(207)
Income taxes payable			(94)
Deferred revenue			(967)
Other accrued expenses and current liabilities			(1,030)
Total current liabilities			(2,621)
Other long-term liabilities			(1,781)
Purchase price, total			15,820
Qelp [Member] | EMEA [Member] | As Initially Reported [Member]
Business Acquisition [Line Items]
Cash and cash equivalents			450
Receivables			1,541
Prepaid expenses			24
Total current assets			2,015
Property and equipment			2,168
Goodwill			9,574
Intangibles			6,000
Deferred charges and other assets			55
Short-term debt			(323)
Accrued employee compensation and benefits			(207)
Income taxes payable			(62)
Deferred revenue			(967)
Other accrued expenses and current liabilities			(1,030)
Total current liabilities			(2,589)
Other long-term liabilities			(1,403)
Purchase price, total			15,820
Qelp [Member] | EMEA [Member] | Measurement Period Adjustments [Member]
Business Acquisition [Line Items]
Receivables			(70)
Total current assets			(70)
Goodwill			480
Income taxes payable			(32)
Total current liabilities			(32)
Other long-term liabilities			$ (378)