Income Taxes - Provision for Income Taxes and Statutory and Effective (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Oct. 31, 2016	Jul. 31, 2016	Apr. 30, 2016	Jan. 31, 2016	Oct. 31, 2015	Jul. 31, 2015	Apr. 30, 2015	Jan. 31, 2015	Oct. 31, 2016	Oct. 31, 2015	Oct. 31, 2014
Current:
U.S. - Federal									$ (119.0)	$ 119.1	$ 274.4
U.S. - State									4.4	5.4	7.9
Foreign									17.1	20.1	21.2
Total current									(97.5)	144.6	303.5
Deferred:
U.S. - Federal									273.4	121.2	(33.7)
U.S. - State									(0.7)	1.7	0.6
Foreign									5.1	2.4	(9.8)
Total deferred									277.8	125.3	(42.9)
Provision for income taxes	$ 40.9	$ 51.2	$ 39.3	$ 48.9	$ 64.4	$ 71.1	$ 67.7	$ 66.7	$ 180.3	269.9	260.6
Comparison of the Statutory and Effective Income Tax Provision
U.S. federal income tax provision statutory rate (as a percent)									35.00%
U.S. federal income tax provision at a statutory rate of 35 percent									$ 182.0	268.4	281.0
Increase (Decrease) Resulting from:
Municipal lease income not taxable									(1.4)	(1.4)	(1.4)
Tax rates on foreign earnings									(5.9)	(6.0)	(8.0)
Foreign tax benefit											(23.1)
State and local income taxes, net of federal income tax benefit									2.4	4.6	5.5
Other - net									3.2	4.3	6.6
Provision for income taxes	40.9	$ 51.2	$ 39.3	$ 48.9	$ 64.4	$ 71.1	$ 67.7	$ 66.7	180.3	$ 269.9	$ 260.6
Accumulated earnings of certain subsidiaries outside the U.S. for which no provision for U.S. income or foreign withholding taxes has been made	360.7								360.7
Provision for income and withholding taxes on accumulated earnings in certain subsidiaries outside the U.S.	0.0								0.0
Cash and cash equivalents held by foreign subsidiaries	$ 85.0								$ 85.0