Acquisitions - Unaudited Proforma Information (Details) - Boat Holdings, LLC - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Business Acquisition [Line Items]
Net sales	$ 1,651,415	$ 1,593,659	$ 4,802,580	$ 4,410,691
Net income	$ 99,224	$ 81,473	$ 268,660	$ 149,517
Basic earnings per share (in dollars per share)	$ 1.60	$ 1.30	$ 4.27	$ 2.38
Diluted earnings per common share (in dollars per share)	$ 1.56	$ 1.28	$ 4.16	$ 2.34