New Accounting Standards New Accounting Standards (Impact of adoption of ASU 2014-09) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 24, 2017	Sep. 30, 2018	Sep. 24, 2017	Jan. 01, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle
Motorcycles and Related Products	$ 1,123,945	$ 962,136	$ 4,013,013	$ 3,867,982
Motorcycles and Related Products cost of goods sold	776,530	687,823	2,659,740	2,545,884
Operating income	149,416	94,412	709,780	782,881
Income before provision for income taxes	141,192	89,895	690,739	769,012
Provision for income taxes	27,337	21,686	159,783	255,567
Net income	113,855	68,209	530,956	513,445
Other current assets	151,042	182,416	151,042	182,416		$ 175,853
Deferred income taxes	63,559	180,575	63,559	180,575		109,073
Accrued liabilities	564,832	573,958	564,832	573,958		529,822
Retained earnings	1,958,445	$ 1,660,997	1,958,445	$ 1,660,997		$ 1,607,570
Calculated under Revenue Guidance in Effect before Topic 606 | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle
Motorcycles and Related Products	1,125,698		3,994,066
Motorcycles and Related Products cost of goods sold	775,831		2,640,454
Operating income	151,868		710,119
Income before provision for income taxes	143,644		691,078
Provision for income taxes	27,931		159,865
Net income	115,713		531,213
Other current assets	186,784		186,784
Deferred income taxes	65,407		65,407
Accrued liabilities	608,189		608,189
Retained earnings	1,952,678		1,952,678
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle
Motorcycles and Related Products	(1,753)		18,947
Motorcycles and Related Products cost of goods sold	699		19,286
Operating income	(2,452)		(339)
Income before provision for income taxes	(2,452)		(339)
Provision for income taxes	(594)		(82)
Net income	(1,858)		(257)
Other current assets	(35,742)		(35,742)
Deferred income taxes	(1,848)		(1,848)
Accrued liabilities	(43,357)		(43,357)
Retained earnings	$ 5,767		$ 5,767		$ 6,000