Goodwill and Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Goodwill [Line Items]
Amortization of intangible assets	$ 3,524	$ 3,266	$ 10,732	$ 10,146
FolioDynamix
Goodwill [Line Items]
Impairment loss					$ 39,700
GovDelivery | Discontinued operations, held-for-sale
Goodwill [Line Items]
Decrease to goodwill from discontinued operations					5,600
Decrease to intangible assets, net					$ 9,000
Decrease to amortization of intangible assets from discontinued operations	$ 500	$ 1,400	$ 500	$ 1,300