Finance Receivables - Recorded Investment Of Retail and Wholesale Finance Receivables By Credit Quality Indicator (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Credit Quality Indicator [Line Items]
Total financing receivables	$ 6,833,944	$ 7,572,947	$ 7,411,816	$ 7,157,557	$ 7,008,801
Wholesale
Financing Receivable, Credit Quality Indicator [Line Items]
2020	391,151
2019	72,048
2018	13,443
2017	7,887
2016	2,297
2015 & Prior	2,923
Total financing receivables	489,749	1,156,519	$ 1,083,615	$ 1,016,957	$ 1,026,590
Wholesale | Non-Performing
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
2015 & Prior	0
Total financing receivables	0
Wholesale | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
2015 & Prior	0
Total financing receivables	0	11,664
Wholesale | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
2015 & Prior	0
Total financing receivables	0	6,122
Wholesale | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2020	658
2019	365
2018	31
2017	0
2016	0
2015 & Prior	0
Total financing receivables	1,054	16,125
Wholesale | Risk Level, Medium [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,925
2019	242
2018	0
2017	0
2016	0
2015 & Prior	0
Total financing receivables	2,167	16,800
Wholesale | Medium Risk
Financing Receivable, Credit Quality Indicator [Line Items]
2020	388,568
2019	71,441
2018	13,412
2017	7,887
2016	2,297
2015 & Prior	2,923
Total financing receivables	$ 486,528	$ 1,105,808