Investment in Other Affiliates (Detail) (USD $)	3 Months Ended		6 Months Ended			3 Months Ended	9 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 Brammo, Inc.	Jun. 30, 2013 Eicher -Polaris Private Limited	Jun. 30, 2013 Eicher -Polaris Private Limited	Dec. 31, 2012 Eicher -Polaris Private Limited	Jun. 30, 2013 Brammo, Inc.	Dec. 31, 2012 Brammo, Inc.	Jun. 30, 2013 Eicher -Polaris Private Limited	Dec. 31, 2012 Eicher -Polaris Private Limited	Jun. 30, 2013 Other affiliates	Dec. 31, 2012 Other affiliates
Investments in and Advances to Affiliates [Line Items]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures					$ 2,500,000				$ 14,500,000	$ 12,000,000	$ 3,401,000	$ 817,000	$ 17,901,000	$ 12,817,000
Equity method investment ownership percentage								50.00%
Period for proportionate share of income (loss) to be reflected in consolidated financials						1 month
Joint venture investment						50,000,000
Investment maturity period						3 years
Investment in affiliates							4,562,000
Equity in loss of other affiliates	$ (586,000)	$ 0	$ (998,000)	$ 0		$ (586,000)