Consolidated Statements of Shareholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Comprehensive Income
Balance at Sep. 30, 2010	$ 2,807,465	$ 10,706	$ 191,900	$ 2,547,917	$ 84,107	$ (27,165)
Balance (in shares) at Sep. 30, 2010						1,239,000
Balance (in shares) at Sep. 30, 2010		107,058,000
Comprehensive Income:
Net income	434,186			434,186			434,186
Other comprehensive income (loss):
Change in value on available-for-sale securities, net of income taxes	18,414				18,414		18,414
Amortization of net periodic benefit costs - net of actuarial gain (loss)	(3,613)				(3,613)		(3,613)
Other comprehensive income (loss)	14,801						14,801
Comprehensive income	448,987						448,987
Dividends declared ($1.30, $.28 and $.26 per share for the years ended 2013, 2012 and 2011, respectively)	(27,893)			(27,893)
Exercise of stock options	15,441	18	(3,942)			19,365
Exercise of stock options (in shares)		185,000				(948,000)
Tax benefit of stock-based awards, including excess tax benefits of $10.7, $3.6 and $13.4 million for the years ended 2013, 2012 and 2011, respectively	13,946		13,946
Stock issued for vested restricted stock, net of shares withheld for employee taxes			(3,096)			3,096
Stock issued for vested restricted stock, net of shares withheld for employee taxes (in shares)						(134,000)
Stock-based compensation	12,101		12,101
Balance at Sep. 30, 2011	3,270,047	10,724	210,909	2,954,210	98,908	(4,704)
Balance (in shares) at Sep. 30, 2011						157,000
Balance (in shares) at Sep. 30, 2011		107,243,000
Comprehensive Income:
Net income	581,045			581,045			581,045
Other comprehensive income (loss):
Change in value on available-for-sale securities, net of income taxes	63,725				63,725		63,725
Amortization of net periodic benefit costs - net of actuarial gain (loss)	4,174				4,174		4,174
Other comprehensive income (loss)	67,899						67,899
Comprehensive income	648,944						648,944
Dividends declared ($1.30, $.28 and $.26 per share for the years ended 2013, 2012 and 2011, respectively)	(29,960)			(29,960)
Exercise of stock options	2,673	32	5,398			(2,757)
Exercise of stock options (in shares)		315,000				47,000
Tax benefit of stock-based awards, including excess tax benefits of $10.7, $3.6 and $13.4 million for the years ended 2013, 2012 and 2011, respectively	4,340		4,340
Stock issued for vested restricted stock, net of shares withheld for employee taxes	(1,514)	4	(2,485)			967
Stock issued for vested restricted stock, net of shares withheld for employee taxes (in shares)		41,000				(51,000)
Repurchase of common stock	(77,610)					(77,610)
Repurchase of common stock (in shares)	1,747,819					1,748,000
Stock-based compensation	18,078		18,078
Balance at Sep. 30, 2012	3,834,998	10,760	236,240	3,505,295	166,807	(84,104)
Balance (in shares) at Sep. 30, 2012	1,901,196					1,901,000
Balance (in shares) at Sep. 30, 2012	107,598,889	107,599,000
Comprehensive Income:
Net income	736,639			736,639			736,639
Other comprehensive income (loss):
Change in value on available-for-sale securities, net of income taxes	(45,690)				(45,690)		(45,690)
Amortization of net periodic benefit costs - net of actuarial gain (loss)	11,413				11,413		11,413
Other comprehensive income (loss)	(34,277)						(34,277)
Comprehensive income	702,362						702,362
Dividends declared ($1.30, $.28 and $.26 per share for the years ended 2013, 2012 and 2011, respectively)	(139,271)			(139,271)
Exercise of stock options	13,317	106	21,746			(8,535)
Exercise of stock options (in shares)		1,057,000				162,000
Tax benefit of stock-based awards, including excess tax benefits of $10.7, $3.6 and $13.4 million for the years ended 2013, 2012 and 2011, respectively	10,727		10,727
Stock issued for vested restricted stock, net of shares withheld for employee taxes	(1,677)	8	(3,226)			1,541
Stock issued for vested restricted stock, net of shares withheld for employee taxes (in shares)		83,000				(41,000)
Repurchase of common stock (in shares)	0
Stock-based compensation	23,271		23,271
Balance at Sep. 30, 2013	$ 4,443,727	$ 10,874	$ 288,758	$ 4,102,663	$ 132,530	$ (91,098)
Balance (in shares) at Sep. 30, 2013	2,021,607					2,022,000
Balance (in shares) at Sep. 30, 2013	108,738,577	108,739,000