Segment Information - Company's Segments Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Jan. 31, 2013	Oct. 31, 2012	Jul. 31, 2012	Apr. 30, 2012	Jan. 31, 2012	Oct. 31, 2011	Jul. 31, 2011	Apr. 30, 2011	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2011
Net sales:
Net sales	$ 1,235,769	$ 852,741	$ 886,569	$ 819,170	$ 1,187,440	$ 821,767	$ 872,712	$ 761,018	$ 3,794,249	$ 3,642,937	$ 3,085,290
Earnings (losses) from operations:
Earnings (losses) from operations									823,638	878,910	728,246
Americas [Member]
Net sales:
Net sales									1,839,969	1,805,783	1,574,571
Earnings (losses) from operations:
Earnings (losses) from operations									345,917	387,951	340,331
Asia-Pacific [Member]
Net sales:
Net sales									810,420	748,214	549,197
Earnings (losses) from operations:
Earnings (losses) from operations									188,510	205,711	133,448
Japan [Member]
Net sales:
Net sales									639,185	616,505	546,537
Earnings (losses) from operations:
Earnings (losses) from operations									204,510	184,767	162,800
Europe [Member]
Net sales:
Net sales									432,167	421,141	360,831
Earnings (losses) from operations:
Earnings (losses) from operations									90,955	105,728	88,309
Total reportable segments [Member]
Net sales:
Net sales									3,721,741	3,591,643	3,031,136
Earnings (losses) from operations:
Earnings (losses) from operations									829,892	884,157	724,888
Other [Member]
Net sales:
Net sales									72,508	51,294	54,154
Earnings (losses) from operations:
Earnings (losses) from operations									$ (6,254)	$ (5,247)	$ 3,358