Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Oct. 31, 2011	Oct. 31, 2010	Oct. 31, 2011	Oct. 31, 2010
Net sales:
Net sales	$ 821,767	$ 681,729	$ 2,455,497	$ 1,984,075
Earnings (losses) from operations:
Earnings from operations for segments	175,621	133,866	558,426	409,101
All non-reportable segments [Member]
Net sales:
Net sales	11,869	14,632	39,401	38,860
Earnings (losses) from operations:
Earnings from operations for segments	(1,986)	2,134	(374)	3,244
Total reportable segments [Member]
Net sales:
Net sales	809,898	667,097	2,416,096	1,945,215
Earnings (losses) from operations:
Earnings from operations for segments	177,607	131,732	558,800	405,857
Americas [Member]
Net sales:
Net sales	387,713	331,767	1,200,588	997,458
Earnings (losses) from operations:
Earnings from operations for segments	64,716	51,678	233,812	175,570
Asia-Pacific [Member]
Net sales:
Net sales	183,220	127,057	523,708	360,883
Earnings (losses) from operations:
Earnings from operations for segments	50,469	25,434	145,809	81,974
Japan [Member]
Net sales:
Net sales	146,437	130,817	412,297	363,897
Earnings (losses) from operations:
Earnings from operations for segments	43,137	39,081	115,944	101,305
Europe [Member]
Net sales:
Net sales	92,528	77,456	279,503	222,977
Earnings (losses) from operations:
Earnings from operations for segments	$ 19,285	$ 15,539	$ 63,235	$ 47,008