Significant Accounting Policies Activity in Polaris Accrued Warranty Reserve (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Activity in Product Warranty Reserve [Roll Forward]
Balance at beginning of period	$ 134,200	$ 132,800	$ 136,200	$ 121,800
Additions charged to expense	37,200	31,400	91,200	94,300
Warranty claims paid, net	(30,800)	(27,100)	(86,800)	(87,800)
Balance at end of period	140,600	137,100	140,600	137,100
Standard Product Warranty Accrual, Additions from Business Acquisition	$ 0	$ 0	$ 0	$ 8,800