Debt Senior Notes (Details)	3 Months Ended	12 Months Ended									12 Months Ended
	Oct. 31, 2014 USD ($)	Jan. 31, 2015 USD ($)	Jan. 31, 2014 USD ($)	Jan. 31, 2013 USD ($)	Jan. 31, 2015 2009 10.00% Series A, due April 2018 [Member] USD ($)	Jan. 31, 2015 2008 9.05% Series A, due December 2015 [Member] USD ($)	Jan. 31, 2015 2009 10.00% Series A, due February 2017 [Member] USD ($)	Jan. 31, 2015 2009 10.00% Series B, due February 2019 [Member] USD ($)	Jan. 31, 2015 2010 1.72% Notes, due September 2016 [Member]	Jan. 31, 2014 2010 1.72% Notes, due September 2016 [Member] JPY (¥)	Jan. 31, 2014 2012 4.40% Series B Notes, due July 2042 [Member] USD ($)	Jan. 31, 2015 2012 4.40% Series B Notes, due July 2042 [Member]	Jan. 31, 2013 2012 4.40% Series B Notes, due July 2042 [Member] USD ($)	Jan. 31, 2015 2014 3.80% Senior Notes, due October 2024 [Member] USD ($)	Jan. 31, 2015 2014 4.90% Senior Notes, due October 2044 [Member] USD ($)
Debt Instrument [Line Items]
Loss on Extinguishment of Debt	$ (93,779,000)	$ (93,779,000)	$ 0	$ 0
Debt Instrument, Periodic Payment, Principal											50,000,000
Debt Instrument, Face Amount					50,000,000	100,000,000	125,000,000	125,000,000		10,000,000,000			250,000,000	250,000,000	300,000,000
Proceeds from issuance of long-term debt		$ 548,037,000	$ 0	$ 250,000,000
Debt Instrument, Interest Rate, Stated Percentage					10.00%	9.05%	10.00%	10.00%	1.72%			4.40%		3.80%	4.90%
Debt Instrument, Interest Rate, Effective Percentage														3.836%	4.926%