CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (UNAUDITED) (USD $) In Thousands, unless otherwise specified	Total	Common Stock	Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income	Treasury Stock
Balance, Beginning of period at Sep. 30, 2012	$ 1,899,752	$ 129,950	$ 1,586,295	$ 480,780	$ 13,306	$ (310,579)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	108,598			108,598
Other comprehensive income adjustment	(8,175)				(8,175)
Dividends paid on common stock	(27,591)			(27,591)
Compensation expense related to common stock options	900		900
Proceeds from exercise of common stock options	297	26	271
Proceeds from issuance of common stock	33,491	1,996	31,495
Restricted stock	2,657	418	2,239
Treasury stock acquired	(87,037)					(87,037)
Balance, End of period at Jun. 30, 2013	1,922,892	132,390	1,621,200	561,787	5,131	(397,616)
Balance, Beginning of period at Sep. 30, 2013	1,937,635	132,573	1,625,051	594,450	6,378	(420,817)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	116,803			116,803
Other comprehensive income adjustment	18,043				18,043
Dividends paid on common stock	(31,393)			(31,393)
Compensation expense related to common stock options	900		900
Proceeds from exercise of common stock options	10,358	759	9,599
Restricted stock	2,520		2,520
Treasury stock acquired	(64,231)					(64,231)
Balance, End of period at Jun. 30, 2014	$ 1,990,635	$ 133,332	$ 1,638,070	$ 679,860	$ 24,421	$ (485,048)