Business Acquisitions (Detail) - USD ($) $ in Thousands			3 Months Ended
	Apr. 03, 2018	Mar. 26, 2018	Sep. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill			$ 911,260	$ 909,811	$ 909,811
Fishing Hot Spots [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred		$ 7,100
Identifiable Intangible assets			2,200
Goodwill			4,700
Fishidy [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred	$ 7,100
Payments for Purchase of Other Assets	$ 7,100
Other minority interest investments [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred			$ 15,500