Financial Information for Polaris Acceptance Reflecting Effects of Securitization Facility (Detail) (Polaris Acceptance, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Polaris Acceptance
Schedule of Investments [Line Items]
Revenues	$ 8,811	$ 13,018	$ 12,459
Interest and operating expenses	1,013	4,131	3,311
Net income	7,798	8,887	9,148
Finance receivables, net	166,025	90,788
Other assets	100	73
Total Assets	166,125	90,861
Notes payable/(receivable)	44,494	(2,435)
Other liabilities	7,655	8,794
Partners' capital	113,976	84,502
Total Liabilities and Partners' Capital	$ 166,125	$ 90,861