3. Securitization Trust Debt (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Dec. 31, 2018
"Securitization trust debt," and components of debt
Receivables Pledged at end of period	[1]	$ 2,216,482
Initial Principal		4,867,818
Outstanding Principal		$ 2,121,010	$ 2,075,409
CPS 2014-A [Member]
"Securitization trust debt," and components of debt
Final Scheduled Payment Date	[2]	June 2021
Receivables Pledged at end of period	[1]	$ 14,133
Initial Principal		180,000
Outstanding Principal		$ 12,508	15,328
Weighted Average Contractual Interest Rate		5.61%
CPS 2014-B [Member]
"Securitization trust debt," and components of debt
Final Scheduled Payment Date	[2]	September 2021
Receivables Pledged at end of period	[1]	$ 21,787
Initial Principal		202,500
Outstanding Principal		$ 20,232	24,051
Weighted Average Contractual Interest Rate		4.65%
CPS 2014-C [Member]
"Securitization trust debt," and components of debt
Final Scheduled Payment Date	[2]	December 2021
Receivables Pledged at end of period	[1]	$ 36,289
Initial Principal		273,000
Outstanding Principal		$ 35,052	40,896
Weighted Average Contractual Interest Rate		4.64%
CPS 2014-D [Member]
"Securitization trust debt," and components of debt
Final Scheduled Payment Date	[2]	March 2022
Receivables Pledged at end of period	[1]	$ 41,339
Initial Principal		267,500
Outstanding Principal		$ 40,388	46,489
Weighted Average Contractual Interest Rate		5.04%
CPS 2015-A [Member]
"Securitization trust debt," and components of debt
Final Scheduled Payment Date	[2]	June 2022
Receivables Pledged at end of period	[1]	$ 47,303
Initial Principal		245,000
Outstanding Principal		$ 45,458	52,448
Weighted Average Contractual Interest Rate		4.75%
CPS 2015-B [Member]
"Securitization trust debt," and components of debt
Final Scheduled Payment Date	[2]	September 2022
Receivables Pledged at end of period	[1]	$ 57,357
Initial Principal		250,000
Outstanding Principal		$ 57,155	64,591
Weighted Average Contractual Interest Rate		4.63%
CPS 2015-C [Member]
"Securitization trust debt," and components of debt
Final Scheduled Payment Date	[2]	December 2022
Receivables Pledged at end of period	[1]	$ 81,433
Initial Principal		300,000
Outstanding Principal		$ 81,046	90,639
Weighted Average Contractual Interest Rate		5.07%
CPS 2016-A [Member]
"Securitization trust debt," and components of debt
Final Scheduled Payment Date	[2]	March 2023
Receivables Pledged at end of period	[1]	$ 107,558
Initial Principal		329,460
Outstanding Principal		$ 107,099	119,444
Weighted Average Contractual Interest Rate		5.34%
CPS 2016-B [Member]
"Securitization trust debt," and components of debt
Final Scheduled Payment Date	[2]	June 2023
Receivables Pledged at end of period	[1]	$ 124,008
Initial Principal		332,690
Outstanding Principal		$ 121,767	135,688
Weighted Average Contractual Interest Rate		5.65%
CPS 2016-C [Member]
"Securitization trust debt," and components of debt
Final Scheduled Payment Date	[2]	September 2023
Receivables Pledged at end of period	[1]	$ 124,638
Initial Principal		318,500
Outstanding Principal		$ 122,374	136,114
Weighted Average Contractual Interest Rate		5.42%
CPS 2016-D [Member]
"Securitization trust debt," and components of debt
Final Scheduled Payment Date	[2]	April 2024
Receivables Pledged at end of period	[1]	$ 96,524
Initial Principal		206,325
Outstanding Principal		$ 95,229	104,645
Weighted Average Contractual Interest Rate		4.01%
CPS 2017-A [Member]
"Securitization trust debt," and components of debt
Final Scheduled Payment Date	[2]	April 2024
Receivables Pledged at end of period	[1]	$ 104,432
Initial Principal		206,320
Outstanding Principal		$ 102,812	113,527
Weighted Average Contractual Interest Rate		4.20%
CPS 2017-B [Member]
"Securitization trust debt," and components of debt
Final Scheduled Payment Date	[2]	December 2023
Receivables Pledged at end of period	[1]	$ 127,462
Initial Principal		225,170
Outstanding Principal		$ 115,265	127,726
Weighted Average Contractual Interest Rate		3.57%
CPS 2017-C [Member]
"Securitization trust debt," and components of debt
Final Scheduled Payment Date	[2]	September 2024
Receivables Pledged at end of period	[1]	$ 128,546
Initial Principal		224,825
Outstanding Principal		$ 118,607	131,845
Weighted Average Contractual Interest Rate		3.52%
CPS 2017-D [Member]
"Securitization trust debt," and components of debt
Final Scheduled Payment Date	[2]	June 2024
Receivables Pledged at end of period	[1]	$ 129,052
Initial Principal		196,300
Outstanding Principal		$ 120,481	132,919
Weighted Average Contractual Interest Rate		3.24%
CPS 2018-A [Member]
"Securitization trust debt," and components of debt
Final Scheduled Payment Date	[2]	March 2025
Receivables Pledged at end of period	[1]	$ 138,374
Initial Principal		190,000
Outstanding Principal		$ 130,064	142,643
Weighted Average Contractual Interest Rate		3.22%
CPS 2018-B [Member]
"Securitization trust debt," and components of debt
Final Scheduled Payment Date	[2]	December 2024
Receivables Pledged at end of period	[1]	$ 161,062
Initial Principal		201,823
Outstanding Principal		$ 154,845	167,809
Weighted Average Contractual Interest Rate		3.65%
CPS 2018-C [Member]
"Securitization trust debt," and components of debt
Final Scheduled Payment Date	[2]	September 2025
Receivables Pledged at end of period	[1]	$ 195,981
Initial Principal		230,275
Outstanding Principal		$ 187,282	204,418
Weighted Average Contractual Interest Rate		3.72%
CPS 2018-D [Member]
"Securitization trust debt," and components of debt
Final Scheduled Payment Date	[2]	June 2025
Receivables Pledged at end of period	[1]	$ 222,304
Initial Principal		233,730
Outstanding Principal		$ 207,198	224,189
Weighted Average Contractual Interest Rate		3.79%
CPS 2019-A [Member]
"Securitization trust debt," and components of debt
Final Scheduled Payment Date	[2]	March 2026
Receivables Pledged at end of period	[1]	$ 256,900
Initial Principal		254,400
Outstanding Principal		$ 246,148	$ 0
Weighted Average Contractual Interest Rate		3.76%

[1] Includes repossessed assets that are included in Other assets on our Unaudited Condensed Consolidated Balance Sheet.

[2] The Final Scheduled Payment Date represents final legal maturity of the securitization trust debt. Securitization trust debt is expected to become due and to be paid prior to those dates, based on amortization of the finance receivables pledged to the trusts. Expected payments, which will depend on the performance of such receivables, as to which there can be no assurance, are $622.1 million in 2019, $649.4 million in 2020, $431.5 million in 2021, $236.3 million in 2022, $150.3 million in 2023, $19.4 million in 2024.