Condensed Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock [Member]	Common Stock [Member] Cumulative Effect, Period of Adoption, Adjustment	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member] Cumulative Effect, Period of Adoption, Adjustment	Retained Earnings [Member]	Retained Earnings [Member] Cumulative Effect, Period of Adoption, Adjustment	Treasury Stock [Member]	Treasury Stock [Member] Cumulative Effect, Period of Adoption, Adjustment	AOCI Attributable to Parent [Member]	AOCI Attributable to Parent [Member] Cumulative Effect, Period of Adoption, Adjustment	Noncontrolling Interest [Member]	Noncontrolling Interest [Member] Cumulative Effect, Period of Adoption, Adjustment
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Oct. 31, 2018	$ 4,768,912		$ 1,779		$ 727,053		$ 5,161,551		$ (1,130,878)		$ 694		$ 8,713
Stockholders' Equity, Period Increase (Decrease)		$ (17,987)						$ (17,987)
Net income	387,692						387,692
Purchase of treasury stock	(167,474)								(167,474)
Exercise of stock options and stock based compensation issuances	4,461				(21,951)				26,412
Employee stock purchase plan issuances	976				(42)				1,018
Stock-based compensation	19,351				19,351
Dividends declared	(48,301)						(48,301)
Other comprehensive income	168										168
Net Income (Loss) Attributable to Noncontrolling Interest	(5)												(5)
Capital contributions	36,664												36,664
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Jul. 31, 2019	4,984,457		1,779		724,411		5,482,955		(1,270,922)		862		45,372
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Apr. 30, 2019	4,986,240		1,779		721,311		5,352,424		(1,135,166)		806		45,086
Net income	146,318						146,318
Purchase of treasury stock	(142,230)								(142,230)
Exercise of stock options and stock based compensation issuances	3,883				(2,284)				6,167
Employee stock purchase plan issuances	256				(51)				307
Stock-based compensation	5,435				5,435
Dividends declared	(15,787)						(15,787)
Other comprehensive income	56										56
Net Income (Loss) Attributable to Noncontrolling Interest	(1)												(1)
Capital contributions	287												287
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Jul. 31, 2019	4,984,457		1,779		724,411		5,482,955		(1,270,922)		862		45,372
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Oct. 31, 2019	5,118,693		1,529		726,879		4,774,422		(425,183)		(5,831)		46,877
Net income	247,307						247,307
Purchase of treasury stock	(633,873)								(633,873)
Exercise of stock options and stock based compensation issuances	10,188				(24,687)				34,875
Employee stock purchase plan issuances	1,062				(713)				1,775
Stock-based compensation	20,636				20,636
Dividends declared	(42,897)						(42,897)
Other comprehensive income	835										835
Net Income (Loss) Attributable to Noncontrolling Interest	(6)												(6)
Capital contributions	4,183												4,183
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Jul. 31, 2020	4,726,128		1,529		722,115		4,978,832		(1,022,406)		(4,996)		51,054
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Apr. 30, 2020	4,613,722		1,529		725,246		4,878,017		(1,034,999)		(5,275)		49,204
Net income	114,761						114,761
Purchase of treasury stock	(320)								(320)
Exercise of stock options and stock based compensation issuances	5,615				(6,858)				12,473
Employee stock purchase plan issuances	333				(107)				440
Stock-based compensation	3,834				3,834
Dividends declared	(13,946)						(13,946)
Other comprehensive income	279										279
Net Income (Loss) Attributable to Noncontrolling Interest	2												2
Capital contributions	1,848												1,848
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Jul. 31, 2020	$ 4,726,128		$ 1,529		$ 722,115		$ 4,978,832		$ (1,022,406)		$ (4,996)		$ 51,054