Fair Value of Financial Instruments - Schedule of Carrying Amount and Estimated Fair Value of Finance Receivables (Detail) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Finance receivables:
Original product	$ 1,035,832	$ 1,537,101
Special product, net of allowance	491,597	715,534
Level 3 [Member] | Carrying Amount [Member]
Finance receivables:
Original product	1,035,832	1,537,101
Special product, net of allowance	491,597	715,534
Level 3 [Member] | Fair Value [Member]
Finance receivables:
Original product	7,920,000	8,695,000
Special product, net of allowance	$ 975,000	$ 1,460,000