Finance Receivables - Summary of reconciliation of changes in allowance for credit losses on contracts (Details 1) (USD $)	3 Months Ended		6 Months Ended				3 Months Ended		6 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 Finance receivables	Mar. 31, 2013 Finance receivables	Sep. 30, 2013 Finance receivables Contracts	Sep. 30, 2012 Finance receivables Contracts	Sep. 30, 2013 Finance receivables Contracts	Sep. 30, 2012 Finance receivables Contracts
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period					$ 14,138,637	$ 16,558,569	$ 14,811,173	$ 19,641,656	$ 16,090,652	$ 19,499,208
Current period provision	3,973,104	3,261,721	6,614,895	6,364,987			3,873,216	3,246,998	6,367,646	6,260,674
Losses absorbed							(6,029,363)	(5,295,524)	(10,678,339)	(8,955,368)
Recoveries							823,996	763,687	1,699,063	1,552,303
Balance at end of period					$ 14,138,637	$ 16,558,569	$ 13,479,022	$ 18,356,817	$ 13,479,022	$ 18,356,817