Summary Of Business And Significant Accounting Policies (Revenues By Geographical Region) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Jan. 31, 2012	Oct. 31, 2011	Jul. 31, 2011	Apr. 30, 2011	Jan. 31, 2011	Oct. 31, 2010	Jul. 31, 2010	Apr. 30, 2010	Jan. 31, 2012	Jan. 31, 2011	Jan. 31, 2010
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenues by geographical region	$ 631,913	$ 584,260	$ 546,002	$ 504,364	$ 456,867	$ 429,087	$ 394,372	$ 376,813	$ 2,266,539	$ 1,657,139	$ 1,305,583
Americas [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenues by geographical region									1,540,289	1,135,019	923,823
Europe [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenues by geographical region									408,456	291,784	232,367
Asia Pacific [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenues by geographical region									$ 317,794	$ 230,336	$ 149,393