Finance Receivables - Aging Of Past Due Finance Receivables Including Non Accrual Status Finance Receivables (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018	Jul. 01, 2018
Financing Receivable, Recorded Investment, Past Due
Total Past Due	$ 193,155	$ 229,901	$ 175,754
Total Finance Receivables	7,789,401	7,411,816	7,507,132
Current
Financing Receivable, Recorded Investment, Past Due
Current	7,596,246	7,181,915	7,331,378
31-60 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	120,347	137,467	117,344
61-90 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	40,335	50,098	35,897
Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	32,473	42,336	22,513
Retail
Financing Receivable, Recorded Investment, Past Due
Total Past Due	190,208	228,015	175,020
Total Finance Receivables	6,549,707	6,328,201	6,373,926
Retail | Current
Financing Receivable, Recorded Investment, Past Due
Current	6,359,499	6,100,186	6,198,906
Retail | 31-60 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	119,770	136,945	116,828
Retail | 61-90 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	40,015	49,825	35,763
Retail | Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	30,423	41,245	22,429
Wholesale
Financing Receivable, Recorded Investment, Past Due
Total Past Due	2,947	1,886	734
Total Finance Receivables	1,239,694	1,083,615	1,133,206
Wholesale | Current
Financing Receivable, Recorded Investment, Past Due
Current	1,236,747	1,081,729	1,132,472
Wholesale | 31-60 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	577	522	516
Wholesale | 61-90 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	320	273	134
Wholesale | Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due	$ 2,050	$ 1,091	$ 84