Significant Accounting Policies Activity in Polaris Accrued Warranty Reserve (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Activity in Product Warranty Reserve [Roll Forward]
Balance at beginning of period	$ 116,286	$ 109,852	$ 123,840	$ 119,274
Additions charged to expense	26,141	30,122	42,172	61,816
Warranty claims paid, net	(36,272)	(31,571)	(59,857)	(72,687)
Balance at end of period	$ 106,155	$ 108,403	$ 106,155	$ 108,403
Off Road Vehicle
Product Warranty Liability [Line Items]
Period of warranties provided by Polaris			6 months