Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
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Name:	us-gaap_TreasuryStockValueAcquiredCostMethod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Stockholders' Equity (Share Repurchases) (Details) - USD ($)	3 Months Ended		12 Months Ended
	Apr. 30, 2019	Jan. 31, 2019	Oct. 31, 2018	Mar. 01, 2017	Feb. 28, 2017
Equity [Abstract]
Share Repurchase Program, maximum amount authorized				$ 1,000,000,000.0	$ 500,000,000.0
Average purchase price (in usd per share)		$ 248.70
Number of common stock repurchased, shares	0	24,500	0
Treasury Stock, Value, Acquired, Cost Method		$ 6,100,000
Share Repurchase Program, remaining authorized amount	$ 557,400,000