Business Acquisitions and Divestitures Divestitures (Details 2) - Consumer and Small and Medium-Sized Security Business [Member] - Held-for-sale [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)
Disposal Group, Including Discontinued Operation, Assets [Abstract]
Accounts receivable, net	$ 20,414
Inventories	43,050
Other current assets	1,031
Property and equipment, net	4,888
Goodwill	13,090
Loss on net assets held for sale	(23,488)
Assets held for sale, net	67,344
Disposal Group, Including Discontinued Operation, Liabilities [Abstract]
Accounts payable and accrued expenses	39,544
Liabilities held for sale	$ 39,544