Finance Receivables, Credit Quality Information, and Allowance for Credit Losses - Amortized Cost Basis in Past-Due Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023	Sep. 30, 2023
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 1,819,756	$ 1,771,410	$ 1,751,009
Net finance receivables in nonaccrual status	$ 77,459	$ 66,871
Total net finance receivables	100.00%	100.00%
Net finance receivables in nonaccrual status	4.30%	3.80%
Large Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 1,293,410	$ 1,274,137	1,271,891
Net finance receivables in nonaccrual status	$ 47,993	$ 44,627
Total net finance receivables	100.00%	100.00%
Net finance receivables in nonaccrual status	3.70%	3.50%
Small Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 524,826	$ 493,473	474,181
Net finance receivables in nonaccrual status	$ 29,295	$ 21,850
Total net finance receivables	100.00%	100.00%
Net finance receivables in nonaccrual status	5.60%	4.40%
Retail Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 1,520	$ 3,800	$ 4,937
Net finance receivables in nonaccrual status	$ 171	$ 394
Total net finance receivables	100.00%	100.00%
Net finance receivables in nonaccrual status	11.30%	10.40%
Financing Receivables, Current [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 1,529,171	$ 1,493,341
Past due, Percent	84.10%	84.30%
Financing Receivables, Current [Member] | Large Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 1,101,634	$ 1,084,518
Past due, Percent	85.20%	85.10%
Financing Receivables, Current [Member] | Small Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 426,506	$ 406,203
Past due, Percent	81.30%	82.40%
Financing Receivables, Current [Member] | Retail Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 1,031	$ 2,620
Past due, Percent	67.80%	69.00%
1 to 29 Days Past Due [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 164,568	$ 155,196
Past due, Percent	9.00%	8.80%
1 to 29 Days Past Due [Member] | Large Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 115,341	$ 109,483
Past due, Percent	8.90%	8.60%
1 to 29 Days Past Due [Member] | Small Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 48,969	$ 45,119
Past due, Percent	9.30%	9.10%
1 to 29 Days Past Due [Member] | Retail Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 258	$ 594
Past due, Percent	17.00%	15.60%
Delinquent Accounts 30 to 59 Days [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 35,300	$ 34,756
Past due, Percent	1.90%	1.90%
Delinquent Accounts 30 to 59 Days [Member] | Large Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 21,797	$ 22,587
Past due, Percent	1.70%	1.70%
Delinquent Accounts 30 to 59 Days [Member] | Small Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 13,451	$ 12,053
Past due, Percent	2.50%	2.40%
Delinquent Accounts 30 to 59 Days [Member] | Retail Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 52	$ 116
Past due, Percent	3.40%	3.10%
Delinquent Accounts 60 to 89 Days [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 27,704	$ 31,212
Past due, Percent	1.50%	1.80%
Delinquent Accounts 60 to 89 Days [Member] | Large Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 16,850	$ 19,844
Past due, Percent	1.30%	1.60%
Delinquent Accounts 60 to 89 Days [Member] | Small Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 10,809	$ 11,253
Past due, Percent	2.10%	2.30%
Delinquent Accounts 60 to 89 Days [Member] | Retail Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 45	$ 115
Past due, Percent	3.00%	3.00%
Delinquent Accounts 90 to 119 Days [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 23,964	$ 27,107
Past due, Percent	1.40%	1.50%
Delinquent Accounts 90 to 119 Days [Member] | Large Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 13,998	$ 16,951
Past due, Percent	1.10%	1.30%
Delinquent Accounts 90 to 119 Days [Member] | Small Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 9,920	$ 10,030
Past due, Percent	1.90%	2.00%
Delinquent Accounts 90 to 119 Days [Member] | Retail Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 46	$ 126
Past due, Percent	3.00%	3.20%
Delinquent Accounts 120 to 149 Days [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 22,544	$ 15,317
Past due, Percent	1.20%	0.90%
Delinquent Accounts 120 to 149 Days [Member] | Large Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 13,552	$ 10,938
Past due, Percent	1.00%	0.90%
Delinquent Accounts 120 to 149 Days [Member] | Small Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 8,942	$ 4,247
Past due, Percent	1.70%	0.90%
Delinquent Accounts 120 to 149 Days [Member] | Retail Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 50	$ 132
Past due, Percent	3.30%	3.50%
Delinquent Accounts 150 to 179 Days [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 16,505	$ 14,481
Past due, Percent	0.90%	0.80%
Delinquent Accounts 150 to 179 Days [Member] | Large Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 10,238	$ 9,816
Past due, Percent	0.80%	0.80%
Delinquent Accounts 150 to 179 Days [Member] | Small Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 6,229	$ 4,568
Past due, Percent	1.20%	0.90%
Delinquent Accounts 150 to 179 Days [Member] | Retail Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 38	$ 97
Past due, Percent	2.50%	2.60%
Total Delinquency Accounts [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 126,017	$ 122,873
Past due, Percent	6.90%	6.90%
Total Delinquency Accounts [Member] | Large Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 76,435	$ 80,136
Past due, Percent	5.90%	6.30%
Total Delinquency Accounts [Member] | Small Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 49,351	$ 42,151
Past due, Percent	9.40%	8.50%
Total Delinquency Accounts [Member] | Retail Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Net finance receivables	$ 231	$ 586
Past due, Percent	15.20%	15.40%