Business Acquisitions (Details textual) - USD ($) $ in Thousands		3 Months Ended
	Mar. 26, 2018	Mar. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill		$ 918,292	$ 909,811
Fishing Hot Spots [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred	$ 7,100
Other minority interest investments [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred		$ 9,500
Consumer and Small and Medium-Sized Security Business [Member] | Held-for-sale [Member]
Business Acquisition [Line Items]
Carrying amount of disposal group			$ 28,800