Business Acquisitions and Divestitures (Divestitures Textual) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on sale of Business	$ 0	$ (13,708)	$ (23,588)
Consumer and Small and Medium-Sized Security Business [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Carrying amount of disposal group	$ 28,800
Held-for-sale [Member] | Consumer and Small and Medium-Sized Security Business [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal		13,700
Loss on sale of Business		$ 23,600