Acquisition of eSignLive - Summary of Acquired Intangible Assets as well as Respective Amortization Periods (Detail) - Silanis Technology Inc [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)
Acquired Finite-Lived Intangible Assets [Line Items]
Identifiable Intangible Assets, Estimated fair value	$ 47,400
Tradenames [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Identifiable Intangible Assets, Estimated fair value	$ 2,400
Identifiable Intangible Assets, Weighted average amortization period	10 years
Technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Identifiable Intangible Assets, Estimated fair value	$ 10,000
Identifiable Intangible Assets, Weighted average amortization period	5 years
Non-compete Agreements [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Identifiable Intangible Assets, Estimated fair value	$ 8,000
Identifiable Intangible Assets, Weighted average amortization period	5 years
Customer Relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Identifiable Intangible Assets, Estimated fair value	$ 27,000
Identifiable Intangible Assets, Weighted average amortization period	12 years