Significant Accounting Policies Activity in Polaris Accrued Warranty Reserve (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Accounting Policies [Abstract]
Deferred tax liabilities	$ 3,400		$ 4,000
Activity in Product Warranty Reserve [Roll Forward]
Balance at beginning of period	136,200	$ 121,800
Additions charged to expense	24,200	26,000
Warranty claims paid, net	(27,600)	(31,600)
Balance at end of period	$ 132,800	$ 116,200