Goodwill and Purchased Intangible Assets - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 3,822,000	$ 3,263,000	$ 7,041,000	$ 6,920,000
Estimated future amortization expense remainder of 2014	6,700,000		6,700,000
Estimated future amortization expense 2015	9,200,000		9,200,000
Estimated future amortization expense 2016	6,000,000		6,000,000
Estimated future amortization expense 2017	4,500,000		4,500,000
Estimated future amortization expense 2018	2,800,000		2,800,000
Estimated future amortization expense thereafter	1,100,000		1,100,000
Impairment of intangible asset	0	0	0	1,494,000
Net book value of intangible asset	30,252,000	26,928,000	30,252,000	26,928,000	27,508,000
Nitro Customer List [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Impairment of intangible asset			0	1,500,000
Net book value of intangible asset	$ 200,000		$ 200,000