Goodwill and Other Intangible Assets (Details 3) In Thousands	12 Months Ended
Mar. 31, 2009 JPY (¥)	Mar. 31, 2011 Construction, Mining and Utility Equipment segment [Member] USD ($)	Mar. 31, 2011 Construction, Mining and Utility Equipment segment [Member] JPY (¥)	Mar. 31, 2009 Construction, Mining and Utility Equipment segment [Member] JPY (¥)	Mar. 31, 2011 Industrial Machinery and Others segment [Member] JPY (¥)
Goodwill and Other Intangible Assets (Textuals) [Abstract]
Impairment loss on goodwill	¥ 2,003,000	$ 33,060	¥ 2,744,000	¥ 2,003,000

Loss recognized during the period that results from the write-down of goodwill after comparing the implied fair value of reporting unit goodwill with the carrying amount of that goodwill. Goodwill is assessed at least annually for impairment.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142
-Paragraph 45
-Subparagraph e(2)

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142
-Paragraph 43

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142
-Paragraph 47
-Subparagraph b

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142
-Paragraph 20

Name:	us-gaap_GoodwillImpairmentLoss
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration