Significant Accounting Policies Activity in Polaris Accrued Warranty Reserve (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Activity in Product Warranty Reserve [Roll Forward]
Balance at beginning of period	$ 108,403	$ 76,873	$ 119,274	$ 56,474
Additions to warranty reserve through acquisitions	0	0	0	147
Additions charged to expense	42,039	87,679	103,855	155,210
Warranty claims paid, net	(38,357)	(34,498)	(111,044)	(81,777)
Balance at end of period	$ 112,085	$ 130,054	$ 112,085	$ 130,054
Off Road Vehicle
Product Warranty Liability [Line Items]
Period of warranties provided by Polaris			6 months