Vehicle Service Agreement Liability Vehicle Service Agreement Liability - Narrative (Details)	Mar. 31, 2019
Minimum
Product Warranty Liability [Line Items]
Vehicle service agreement fee, percentage of refund on original amount	9.00%
Maximum
Product Warranty Liability [Line Items]
Vehicle service agreement fee, percentage of refund on original amount	13.00%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration