Intangible Assets - Schedule of Intangible Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Beginning Balance	$ 37,970	$ 12,819
Net foreign currency translation	(115)	(38)
Amortization expense	(8,849)	(4,942)	$ (4,532)
Ending Balance	46,549	37,970	12,819
December 31, 2016 balance at cost				$ 78,746
Accumulated amortization				(32,197)
Ending Balance	37,970	12,819	12,819	46,549
Silanis Technology Inc [Member]
Finite-Lived Intangible Assets [Line Items]
Measurement Period Adjustments - eSignLive	17,400
Additions-eSignLive		30,000
Amortization expense		(6,060)	(6,060)
Other Acquisitions [Member]
Finite-Lived Intangible Assets [Line Items]
Additions-eSignLive	143	131
Capitalized Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Beginning Balance	34,632	10,216
Net foreign currency translation	(58)	(15)
Amortization expense	(4,182)	(4,569)
Ending Balance	11,392	34,632	10,216
December 31, 2016 balance at cost				37,745
Accumulated amortization				(26,353)
Ending Balance	34,632	10,216	10,216	11,392
Capitalized Technology [Member] | Silanis Technology Inc [Member]
Finite-Lived Intangible Assets [Line Items]
Measurement Period Adjustments - eSignLive	(19,000)
Additions-eSignLive		29,000
Capitalized Technology [Member] | Other Acquisitions [Member]
Finite-Lived Intangible Assets [Line Items]
Additions-eSignLive	0	0
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Beginning Balance	828	644
Net foreign currency translation	(57)	(23)
Amortization expense	(2,597)	(193)
Ending Balance	24,774	828	644
December 31, 2016 balance at cost				27,757
Accumulated amortization				(2,983)
Ending Balance	828	644	644	24,774
Customer Relationships [Member] | Silanis Technology Inc [Member]
Finite-Lived Intangible Assets [Line Items]
Measurement Period Adjustments - eSignLive	26,600
Additions-eSignLive		400
Customer Relationships [Member] | Other Acquisitions [Member]
Finite-Lived Intangible Assets [Line Items]
Additions-eSignLive	0	0
Other [Member]
Finite-Lived Intangible Assets [Line Items]
Beginning Balance	2,510	1,959
Net foreign currency translation		0
Amortization expense	(2,070)	(180)
Ending Balance	10,383	2,510	1,959
December 31, 2016 balance at cost				13,244
Accumulated amortization				(2,861)
Ending Balance	2,510	1,959	$ 1,959	$ 10,383
Other [Member] | Silanis Technology Inc [Member]
Finite-Lived Intangible Assets [Line Items]
Measurement Period Adjustments - eSignLive	9,800
Additions-eSignLive		600
Other [Member] | Other Acquisitions [Member]
Finite-Lived Intangible Assets [Line Items]
Additions-eSignLive	$ 143	$ 131