Consolidated Statement Of Shareholders' Equity (USD $) In Thousands, except Share data	Total	Common Stock [Member]	Accumulated Other Comprehensive Income/(Loss) [Member]	Retained Earnings [Member]
Balance at Sep. 30, 2011	$ 1,105,436	$ 380,737	$ (6,422)	$ 731,121
Balance, shares at Sep. 30, 2011		79,145,000
Exercise of employee stock options	1,130	1,130
Exercise of employee stock options, shares		120,000
Issuance of stock under employee stock purchase plan	24,043	24,043
Issuance of stock under employee stock purchase plan, shares		281,000
Issuance of restricted stock, shares		832,000
Repurchase of common stock	(184,776)	(184,776)
Repurchase of common stock, shares		(1,663,000)
Tax benefit from employee stock transactions	10,440	10,440
Stock-based compensation	95,348	95,348
Net income	275,186			275,186
Other comprehensive gain (loss)	2,593		2,593
Balance at Sep. 30, 2012	1,329,400	326,922	(3,829)	1,006,307
Balance, shares at Sep. 30, 2012		78,715,000
Exercise of employee stock options	1,341	1,341
Exercise of employee stock options, shares		126,000
Issuance of stock under employee stock purchase plan	28,251	28,251
Issuance of stock under employee stock purchase plan, shares		422,000
Issuance of restricted stock, shares		1,094,000
Repurchase of common stock	(200,000)	(200,000)
Repurchase of common stock, shares		(2,267,000)
Tax benefit from employee stock transactions	1,779	1,779
Stock-based compensation	104,212	104,212
Net income	277,314			277,314
Other comprehensive gain (loss)	(3,585)		(3,585)
Balance at Sep. 30, 2013	1,538,712	262,505	(7,414)	1,283,621
Balance, shares at Sep. 30, 2013	78,090,000	78,090,000
Exercise of employee stock options	1,422	1,422
Exercise of employee stock options, shares	149,134	149,000
Issuance of stock under employee stock purchase plan	33,878	33,878
Issuance of stock under employee stock purchase plan, shares		516,000
Issuance of restricted stock, shares		1,228,000
Repurchase of common stock	(650,542)	(418,879)		(231,663)
Repurchase of common stock, shares		(6,593,000)
Tax benefit from employee stock transactions	9,671	9,671
Stock-based compensation	127,156	127,156
Net income	311,183			311,183
Other comprehensive gain (loss)	(2,170)		(2,170)
Balance at Sep. 30, 2014	$ 1,369,310	$ 15,753	$ (9,584)	$ 1,363,141
Balance, shares at Sep. 30, 2014	73,390,000	73,390,000