Goodwill and Other Intangible Assets - Intangible Assets and their Related Useful Lives (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Accumulated amortization	$ (23,330)	$ (22,292)
Intangible assets, net	3,508	4,546
Acquired technology [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	20,441	20,441
Intangible assets, Accumulated amortization	(17,008)	(16,103)
Intangible assets, net	$ 3,433	4,338
Acquired technology [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, useful life	5 years
Acquired technology [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, useful life	7 years
Perpetual software licenses [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, useful life	2 years
Intangible assets, gross	$ 2,430	2,430
Intangible assets, Accumulated amortization	(2,430)	(2,430)
Intangible assets, net	0	0
Covenant not to compete [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	2,028	2,028
Intangible assets, Accumulated amortization	(2,015)	(1,976)
Intangible assets, net	$ 13	52
Covenant not to compete [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, useful life	1 year
Covenant not to compete [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, useful life	4 years
Other [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 1,939	1,939
Intangible assets, Accumulated amortization	(1,877)	(1,783)
Intangible assets, net	$ 62	$ 156
Other [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, useful life	2 years
Other [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, useful life	7 years