Supplemental Consolidating Data (Cash Flows) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 24, 2017	Sep. 30, 2018	Sep. 24, 2017	Dec. 31, 2017	Dec. 31, 2016
Condensed Cash Flow Statements, Captions
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 970,011	$ 746,514	$ 970,011	$ 746,514	$ 746,210	$ 827,131
Cash flows from operating activities:
Net income	113,855	68,209	530,956	513,445
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of intangibles			196,461	163,974
Amortization of deferred loan origination costs			61,213	62,052
Amortization of financing origination fees			6,207	6,112
Provision for long-term employee benefits			28,162	22,427
Employee benefit plan contributions and payments			(11,035)	(43,060)
Stock compensation expense			29,122	25,581
Net change in wholesale finance receivables related to sales			(18,400)	36,678
Provision for credit losses	23,530	29,253	72,462	99,059
Deferred income taxes			1,457	(5,151)
Other, net			29,340	(11,122)
Changes in current assets and liabilities:
Accounts receivable, net			(14,784)	(29,167)
Finance receivables - accrued interest and other			1,374	317
Inventories			8,270	50,016
Accounts payable and accrued liabilities			183,606	88,758
Derivative instruments			1,227	2,752
Other			16,917	(33,596)
Total adjustments			591,599	435,630
Net cash provided by operating activities			1,122,555	949,075
Cash flows from investing activities:
Capital expenditures			(119,845)	(114,022)
Origination of finance receivables			(3,039,160)	(2,927,372)
Collections on finance receivables			2,564,695	2,480,122
Other			(21,753)	7,272
Net cash used by investing activities			(616,063)	(554,000)
Cash flows from financing activities:
Proceeds from issuance of medium-term notes			1,144,018	893,668
Repayments of medium-term notes			(877,488)	(400,000)
Repayments of securitization debt			(224,507)	(367,298)
Net increase (decrease) in credit facilities and unsecured commercial paper			102,154	(225,038)
Borrowings of asset-backed commercial paper			120,903	371,253
Repayments of asset-backed commercial paper			(156,258)	(129,690)
Dividends paid			(186,105)	(190,121)
Purchase of common stock for treasury			(195,998)	(465,167)
Issuance of common stock under employee stock option plans			3,157	7,884
Net cash (used by) provided by financing activities			(270,124)	(504,509)
Effect of exchange rate changes on cash, cash equivalents and restricted cash			(12,567)	28,817
Cash, cash equivalents and restricted cash:
Net increase (decrease) in cash, cash equivalents and restricted cash			223,801	(80,617)
Reportable Legal Entities | Motorcycles And Related Products Operations
Condensed Cash Flow Statements, Captions
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	576,670	311,029	576,670	311,029	338,186	425,540
Cash flows from operating activities:
Net income	49,462	111,379	469,370	580,724
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of intangibles			193,289	158,938
Amortization of deferred loan origination costs			0	0
Amortization of financing origination fees			497	491
Provision for long-term employee benefits			28,162	22,427
Employee benefit plan contributions and payments			(11,035)	(43,060)
Stock compensation expense			26,122	23,223
Net change in wholesale finance receivables related to sales			0	0
Provision for credit losses	0	0	0	0
Deferred income taxes			(2,991)	3,450
Other, net			28,426	(14,671)
Changes in current assets and liabilities:
Accounts receivable, net			(169,168)	(211,115)
Finance receivables - accrued interest and other			0	0
Inventories			8,270	50,016
Accounts payable and accrued liabilities			170,001	75,957
Derivative instruments			1,124	2,708
Other			19,411	(45,830)
Total adjustments			292,108	22,534
Net cash provided by operating activities			761,478	603,258
Cash flows from investing activities:
Capital expenditures			(110,493)	(105,591)
Origination of finance receivables			0	0
Collections on finance receivables			0	0
Other			(21,753)	7,272
Net cash used by investing activities			(132,246)	(98,319)
Cash flows from financing activities:
Proceeds from issuance of medium-term notes			0	0
Repayments of medium-term notes			0	0
Repayments of securitization debt			0	0
Net increase (decrease) in credit facilities and unsecured commercial paper			0	0
Borrowings of asset-backed commercial paper			0	0
Repayments of asset-backed commercial paper			0	0
Dividends paid			(186,105)	(190,121)
Purchase of common stock for treasury			(195,998)	(465,167)
Issuance of common stock under employee stock option plans			3,157	7,884
Net cash (used by) provided by financing activities			(378,946)	(647,404)
Effect of exchange rate changes on cash, cash equivalents and restricted cash			(11,802)	27,954
Cash, cash equivalents and restricted cash:
Net increase (decrease) in cash, cash equivalents and restricted cash			238,484	(114,511)
Reportable Legal Entities | Financial Services Operations
Condensed Cash Flow Statements, Captions
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	393,341	435,485	393,341	435,485	408,024	401,591
Cash flows from operating activities:
Net income	64,462	47,307	171,801	129,322
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of intangibles			3,172	5,036
Amortization of deferred loan origination costs			61,213	62,052
Amortization of financing origination fees			5,710	5,621
Provision for long-term employee benefits			0	0
Employee benefit plan contributions and payments			0	0
Stock compensation expense			3,000	2,358
Net change in wholesale finance receivables related to sales			0	0
Provision for credit losses	23,530	29,253	72,462	99,059
Deferred income taxes			4,343	(8,656)
Other, net			699	2,946
Changes in current assets and liabilities:
Accounts receivable, net			0	0
Finance receivables - accrued interest and other			1,374	317
Inventories			0	0
Accounts payable and accrued liabilities			152,028	199,855
Derivative instruments			103	44
Other			3,173	1,731
Total adjustments			307,277	370,363
Net cash provided by operating activities			479,078	499,685
Cash flows from investing activities:
Capital expenditures			(9,352)	(8,431)
Origination of finance receivables			(5,845,799)	(5,791,241)
Collections on finance receivables			5,363,333	5,386,123
Other			0	0
Net cash used by investing activities			(491,818)	(413,549)
Cash flows from financing activities:
Proceeds from issuance of medium-term notes			1,144,018	893,668
Repayments of medium-term notes			(877,488)	(400,000)
Repayments of securitization debt			(224,507)	(367,298)
Net increase (decrease) in credit facilities and unsecured commercial paper			102,154	(225,038)
Borrowings of asset-backed commercial paper			120,903	371,253
Repayments of asset-backed commercial paper			(156,258)	(129,690)
Dividends paid			(110,000)	(196,000)
Purchase of common stock for treasury			0	0
Issuance of common stock under employee stock option plans			0	0
Net cash (used by) provided by financing activities			(1,178)	(53,105)
Effect of exchange rate changes on cash, cash equivalents and restricted cash			(765)	863
Cash, cash equivalents and restricted cash:
Net increase (decrease) in cash, cash equivalents and restricted cash			(14,683)	33,894
Eliminations
Condensed Cash Flow Statements, Captions
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	0	0	0	0	$ 0	$ 0
Cash flows from operating activities:
Net income	(69)	(90,477)	(110,215)	(196,601)
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of intangibles			0	0
Amortization of deferred loan origination costs			0	0
Amortization of financing origination fees			0	0
Provision for long-term employee benefits			0	0
Employee benefit plan contributions and payments			0	0
Stock compensation expense			0	0
Net change in wholesale finance receivables related to sales			(18,400)	36,678
Provision for credit losses	$ 0	$ 0	0	0
Deferred income taxes			105	55
Other, net			215	603
Changes in current assets and liabilities:
Accounts receivable, net			154,384	181,948
Finance receivables - accrued interest and other			0	0
Inventories			0	0
Accounts payable and accrued liabilities			(138,423)	(187,054)
Derivative instruments			0	0
Other			(5,667)	10,503
Total adjustments			(7,786)	42,733
Net cash provided by operating activities			(118,001)	(153,868)
Cash flows from investing activities:
Capital expenditures			0	0
Origination of finance receivables			2,806,639	2,863,869
Collections on finance receivables			(2,798,638)	(2,906,001)
Other			0	0
Net cash used by investing activities			8,001	(42,132)
Cash flows from financing activities:
Proceeds from issuance of medium-term notes			0	0
Repayments of medium-term notes			0	0
Repayments of securitization debt			0	0
Net increase (decrease) in credit facilities and unsecured commercial paper			0	0
Borrowings of asset-backed commercial paper			0	0
Repayments of asset-backed commercial paper			0	0
Dividends paid			110,000	196,000
Purchase of common stock for treasury			0	0
Issuance of common stock under employee stock option plans			0	0
Net cash (used by) provided by financing activities			110,000	196,000
Effect of exchange rate changes on cash, cash equivalents and restricted cash			0	0
Cash, cash equivalents and restricted cash:
Net increase (decrease) in cash, cash equivalents and restricted cash			$ 0	$ 0