Acquisition - Finalization of Purchase Accounting Related to Acquisition (Detail) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
	Feb. 02, 2015	Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2014
Consideration:
Cash, net of cash received			$ (22,238)
Recognized amounts of identifiable assets acquired and liabilities assumed:
Goodwill		$ 12,025	12,025	$ 12,105	$ 5,231
LinkEx, Inc [Member]
Consideration:
Cash, net of cash received		(22,238)
Fair value of total consideration transferred	$ (22,200)	(22,238)
Acquisition related costs included in SG&A		300	300
Recognized amounts of identifiable assets acquired and liabilities assumed:
Current assets		4,337	4,337
Property and equipment		430	430
Other identifiable intangible assets		2,300	2,300
Other non-current assets		9	9
Current liabilities		(2,900)	(2,900)
Non-current liabilities		(32)	(32)
Total identifiable net assets assumed		15,444	15,444
Goodwill		6,794	6,794
Total		22,238	22,238
LinkEx, Inc [Member] | Customer Lists [Member]
Recognized amounts of identifiable assets acquired and liabilities assumed:
Customer lists		$ 11,300	$ 11,300