CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock [Member]	Additional Paid In Capital [Member]	Accumulated Other Comprehensive Income [Member]	Retained Earnings [Member]
Common shareholders' equity, beginning balance at Sep. 30, 2011	$ 2,255,421	$ 451	$ 1,732,935	$ (48,460)	$ 570,495
Common stock shares outstanding, balance at Sep. 30, 2011		90,296,482
Net income	216,717				216,717
Other comprehensive income (loss)	853			853
Repurchase of common stock, shares		(387,991)
Repurchase of common stock, amount	(12,535)	(2)	(12,533)
Repurchase of equity awards, shares		(153,255)
Repurchase of equity awards, amount	(5,219)	0	(5,219)
Cash dividends	(125,796)				(125,796)
Common stock issued:
Direct stock purchase plan, shares		0
Direct stock purchase plan, amount	(65)	0	(65)
1998 Long-term incentive plan, shares		482,289
1998 Long-term incentive plan, amount	12,037	2	12,519		(484)
Employee stock-based compensation	17,752		17,752
Outside directors stock-for-fee plan, shares		2,375
Outside directors stock-for-fee-plan, amount	78		78
Common shareholders' equity, ending balance at Sep. 30, 2012	2,359,243	451	1,745,467	(47,607)	660,932
Common stock shares outstanding, ending balance at Sep. 30, 2012		90,239,900
Net income	243,194				243,194
Other comprehensive income (loss)	86,485			86,485
Repurchase of equity awards, shares		(133,449)
Repurchase of equity awards, amount	(5,150)	0	(5,150)
Cash dividends	(128,115)				(128,115)
Common stock issued:
Direct stock purchase plan, amount	(50)	0	(50)
1998 Long-term incentive plan, shares		531,672
1998 Long-term incentive plan, amount	8,788	2	9,530		(744)
Employee stock-based compensation	15,934		15,934
Outside directors stock-for-fee plan, shares		2,088
Outside directors stock-for-fee-plan, amount	80		80
Common shareholders' equity, ending balance at Sep. 30, 2013	2,580,409	453	1,765,811	38,878	775,267
Common stock shares outstanding, ending balance at Sep. 30, 2013		90,640,211
Net income	289,817				289,817
Other comprehensive income (loss)	(51,271)			(51,271)
Repurchase of equity awards, shares		(190,134)
Repurchase of equity awards, amount	(8,717)	(1)	(8,716)
Cash dividends	(146,248)				(146,248)
Common stock issued:
Direct stock purchase plan, shares		83,150
Direct stock purchase plan, amount	4,067	1	4,066
1998 Long-term incentive plan, shares		653,130
1998 Long-term incentive plan, amount	4,353	3	5,214		(864)
Employee stock-based compensation	23,536		23,536
Outside directors stock-for-fee plan, shares		1,735
Outside directors stock-for-fee-plan, amount	81		81
Stock Issued During Period, Value, New Issues	390,205	46	390,159
Stock Issued During Period, Shares, New Issues		9,200,000
Common shareholders' equity, ending balance at Sep. 30, 2014	$ 3,086,232	$ 502	$ 2,180,151	$ (12,393)	$ 917,972
Common stock shares outstanding, ending balance at Sep. 30, 2014		100,388,092