Summary of Significant Accounting Policies (New Accounting Standards) (Impact of Adoption of ASU 2017-07) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle
Motorcycles and Related Products cost of goods sold	$ 3,351,796	$ 3,272,330	$ 3,425,997
Selling, administrative and engineering expense	$ 1,258,098	1,180,176	1,213,794
Accounting Standards Update 2017-07 \| Restatement Adjustment [Member]
New Accounting Pronouncements or Change in Accounting Principle
Motorcycles and Related Products cost of goods sold		10,600	6,200
Selling, administrative and engineering expense		$ (1,400)	$ (3,600)

The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.2(a),(d))
-URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227

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The aggregate total costs related to selling a firm's product and services, as well as all other general and administrative expenses. Direct selling expenses (for example, credit, warranty, and advertising) are expenses that can be directly linked to the sale of specific products. Indirect selling expenses are expenses that cannot be directly linked to the sale of specific products, for example telephone expenses, Internet, and postal charges. General and administrative expenses include salaries of non-sales personnel, rent, utilities, communication, etc.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 330
-SubTopic 10
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