Supplemental Consolidating Data (Balance Sheet) (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018	Apr. 01, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 749,600		$ 1,203,766	$ 753,517
Marketable securities	10,003		10,007	0
Accounts receivable, net	353,541		306,474	355,107
Finance receivables, net	2,443,899		2,214,424	2,341,918
Inventories	595,806		556,128	564,571
Restricted cash	43,471		49,275	54,569
Other current assets	177,761		144,368	150,472
Total current assets	4,374,081		4,484,442	4,220,154
Finance receivables, net	4,994,693		5,007,507	4,784,524
Property, plant and equipment, net	876,003		904,132	934,645
Prepaid pension costs	0		0	122,230
Goodwill	64,131		55,048	56,524
Deferred income taxes	132,988		141,464	77,624
Lease assets	55,305	$ 60,000
Other long-term assets	83,412		73,071	81,920
Total assets	10,580,613		10,665,664	10,277,621
Current liabilities:
Accounts payable	380,918		284,861	319,040
Accrued liabilities	644,171		601,130	566,408
Short-term debt	1,192,925		1,135,810	1,036,976
Current portion of long-term debt, net	1,372,050		1,575,799	1,872,679
Total current liabilities	3,590,064		3,597,600	3,795,103
Long-term debt, net	4,744,694		4,887,667	4,108,511
Lease liabilities	39,516
Pension liabilities	98,862		107,776	54,921
Postretirement healthcare benefits	93,897		94,453	113,031
Other long-term liabilities	215,969		204,219	210,106
Shareholders’ equity	1,797,611		1,773,949	1,995,949	$ 1,844,277
Total liabilities and shareholders' equity	10,580,613		10,665,664	10,277,621
Reportable Legal Entities | Motorcycles And Related Products Operations
Current assets:
Cash and cash equivalents	384,390		544,548	403,009
Marketable securities	10,003		10,007
Accounts receivable, net	666,782		425,727	686,265
Finance receivables, net	0		0	0
Inventories	595,806		556,128	564,571
Restricted cash	0		0	0
Other current assets	137,167		91,172	108,613
Total current assets	1,794,148		1,627,582	1,762,458
Finance receivables, net	0		0	0
Property, plant and equipment, net	820,634		847,176	887,522
Prepaid pension costs				122,230
Goodwill	64,131		55,048	56,524
Deferred income taxes	96,500		105,388	36,140
Lease assets	48,513
Other long-term assets	154,687		144,122	145,344
Total assets	2,978,613		2,779,316	3,010,218
Current liabilities:
Accounts payable	351,831		258,587	297,162
Accrued liabilities	544,560		496,643	462,279
Short-term debt	0		0	0
Current portion of long-term debt, net	0		0	0
Total current liabilities	896,391		755,230	759,441
Long-term debt, net	742,791		742,624	742,126
Lease liabilities	32,520
Pension liabilities	98,862		107,776	54,921
Postretirement healthcare benefits	93,897		94,453	113,031
Other long-term liabilities	174,150		164,243	171,389
Shareholders’ equity	940,002		914,990	1,169,310
Total liabilities and shareholders' equity	2,978,613		2,779,316	3,010,218
Reportable Legal Entities | Financial Services Operations
Current assets:
Cash and cash equivalents	365,210		659,218	350,508
Marketable securities	0		0
Accounts receivable, net	0		0	0
Finance receivables, net	2,443,899		2,214,424	2,341,918
Inventories	0		0	0
Restricted cash	43,471		49,275	54,569
Other current assets	40,594		59,070	44,724
Total current assets	2,893,174		2,981,987	2,791,719
Finance receivables, net	4,994,693		5,007,507	4,784,524
Property, plant and equipment, net	55,369		56,956	47,123
Prepaid pension costs				0
Goodwill	0		0	0
Deferred income taxes	37,487		37,603	42,543
Lease assets	6,792
Other long-term assets	19,149		18,680	23,514
Total assets	8,006,664		8,102,733	7,689,423
Current liabilities:
Accounts payable	342,328		145,527	353,036
Accrued liabilities	98,778		110,063	106,149
Short-term debt	1,192,925		1,135,810	1,036,976
Current portion of long-term debt, net	1,372,050		1,575,799	1,872,679
Total current liabilities	3,006,081		2,967,199	3,368,840
Long-term debt, net	4,001,903		4,145,043	3,366,385
Lease liabilities	6,996
Pension liabilities	0		0	0
Postretirement healthcare benefits	0		0	0
Other long-term liabilities	39,070		37,142	35,899
Shareholders’ equity	952,614		953,349	918,299
Total liabilities and shareholders' equity	8,006,664		8,102,733	7,689,423
Eliminations
Current assets:
Cash and cash equivalents	0		0	0
Marketable securities	0		0
Accounts receivable, net	(313,241)		(119,253)	(331,158)
Finance receivables, net	0		0	0
Inventories	0		0	0
Restricted cash	0		0	0
Other current assets	0		(5,874)	(2,865)
Total current assets	(313,241)		(125,127)	(334,023)
Finance receivables, net	0		0	0
Property, plant and equipment, net			0	0
Prepaid pension costs				0
Goodwill			0	0
Deferred income taxes	(999)		(1,527)	(1,059)
Lease assets	0
Other long-term assets	(90,424)		(89,731)	(86,938)
Total assets	(404,664)		(216,385)	(422,020)
Current liabilities:
Accounts payable	(313,241)		(119,253)	(331,158)
Accrued liabilities	833		(5,576)	(2,020)
Short-term debt	0		0	0
Current portion of long-term debt, net	0		0	0
Total current liabilities	(312,408)		(124,829)	(333,178)
Long-term debt, net	0		0	0
Lease liabilities	0
Pension liabilities	0		0	0
Postretirement healthcare benefits	0		0	0
Other long-term liabilities	2,749		2,834	2,818
Shareholders’ equity	(95,005)		(94,390)	(91,660)
Total liabilities and shareholders' equity	$ (404,664)		$ (216,385)	$ (422,020)