Finance Receivables, Credit Quality Information - Aging of receivables (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 12, 2018	Dec. 31, 2017
Past due finance receivables
Total delinquent	$ 11,395	$ 8,711
Total delinquent (as a percent)	11.60%	9.70%
Loans in non-accrural status	$ 1,560	$ 1,598
Gross receivables (as a percent)	1.60%	1.80%
Short-term consumer loans
Past due finance receivables
Loans in non-accrural status	$ 61,973	$ 53,779
Medium-term consumer loans
Past due finance receivables
Loans in non-accrural status	36,357	36,029
Consumer Borrower
Aging of receivables
Current finance receivables	$ 86,935	$ 81,097
Current finance receivables (as a percent)	88.40%	90.30%
Past due finance receivables
Loans in non-accrural status	$ 98,330	$ 89,808	$ 101,380	$ 113,368
Gross receivables (as a percent)	100.00%	100.00%
Consumer Borrower | Past due finance receivables (1 - 30 days)
Past due finance receivables
Total delinquent	$ 8,207	$ 5,748
Total delinquent (as a percent)	8.40%	6.40%
Consumer Borrower | Past due finance receivables (31 - 60 days)
Past due finance receivables
Total delinquent	$ 2,834	$ 2,694
Total delinquent (as a percent)	2.90%	3.00%
Consumer Borrower | Past due finance receivables (more than 61 days)
Past due finance receivables
Total delinquent	$ 354	$ 269
Total delinquent (as a percent)	0.30%	0.30%
Consumer Borrower | Short-term consumer loans
Past due finance receivables
Loans in non-accrural status	$ 61,973	$ 53,779	60,780	66,465
Consumer Borrower | Short-term consumer loans | Past due finance receivables (1 - 30 days)
Past due finance receivables
Total delinquent	$ 2,645	$ 1,078
Total delinquent (as a percent)	2.70%	1.20%
Consumer Borrower | Secure Short Term Consumer Loans [Member] | Past due finance receivables (1 - 30 days)
Past due finance receivables
Total delinquent	$ 1,513	$ 629
Total delinquent (as a percent)	1.50%	0.70%
Consumer Borrower | Unsecure Short Term Consumer Loans [Member] | Past due finance receivables (1 - 30 days)
Past due finance receivables
Total delinquent	$ 1,132	$ 449
Total delinquent (as a percent)	1.20%	0.50%
Consumer Borrower | Medium-term consumer loans
Past due finance receivables
Loans in non-accrural status		$ 36,029	$ 40,600	$ 46,903
Consumer Borrower | Medium-term consumer loans | Past due finance receivables (1 - 30 days)
Past due finance receivables
Total delinquent	$ 5,562	$ 4,670
Total delinquent (as a percent)	5.70%	5.20%
Consumer Borrower | Medium-term consumer loans | Past due finance receivables (31 - 60 days)
Past due finance receivables
Total delinquent	$ 2,834	$ 2,694
Total delinquent (as a percent)	2.90%	3.00%
Consumer Borrower | Medium-term consumer loans | Past due finance receivables (more than 61 days)
Past due finance receivables
Total delinquent	$ 354	$ 269
Total delinquent (as a percent)	0.30%	0.30%
Consumer Borrower | Secure Medium Term Consumer Loans [Member] | Past due finance receivables (1 - 30 days)
Past due finance receivables
Total delinquent	$ 1,321	$ 898
Total delinquent (as a percent)	1.30%	1.00%
Consumer Borrower | Secure Medium Term Consumer Loans [Member] | Past due finance receivables (31 - 60 days)
Past due finance receivables
Total delinquent	$ 461	$ 269
Total delinquent (as a percent)	0.50%	0.30%
Consumer Borrower | Secure Medium Term Consumer Loans [Member] | Past due finance receivables (more than 61 days)
Past due finance receivables
Total delinquent	$ 10	$ 18
Consumer Borrower | Unsecured Medium Term Consumer Loans [Member] | Past due finance receivables (1 - 30 days)
Past due finance receivables
Total delinquent	$ 4,241	$ 3,772
Total delinquent (as a percent)	4.30%	4.20%
Consumer Borrower | Unsecured Medium Term Consumer Loans [Member] | Past due finance receivables (31 - 60 days)
Past due finance receivables
Total delinquent	$ 2,373	$ 2,425
Total delinquent (as a percent)	2.40%	2.70%
Consumer Borrower | Unsecured Medium Term Consumer Loans [Member] | Past due finance receivables (more than 61 days)
Past due finance receivables
Total delinquent	$ 344	$ 251
Total delinquent (as a percent)	0.30%	0.30%