Significant Accounting Policies Activity in Polaris Accrued Warranty Reserve (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Accounting Policies [Abstract]
Deferred tax liabilities	$ 3,300		$ 3,300		$ 4,000
Activity in Product Warranty Reserve [Roll Forward]
Balance at beginning of period	132,800	$ 116,200	136,200	$ 121,800
Additions charged to expense	29,800	36,900	54,000	62,900
Warranty claims paid, net	(28,400)	(29,100)	(56,000)	(60,700)
Balance at end of period	134,200	132,800	134,200	132,800
Standard Product Warranty Accrual, Additions from Business Acquisition	$ 0	$ 8,800	$ 0	$ 8,800