Condensed Consolidated Statement Of Changes In Shareholders' Equity (USD $) In Thousands	Total	Common Stock	Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning Balance at Sep. 30, 2012	$ 1,939,422	$ 65,452	$ 160,540	$ 1,716,441	$ (3,011)
Beginning Balance (in shares) at Sep. 30, 2012		65,452
Net income	158,350			158,350
Other comprehensive gain	826				826
Restricted stock awards		145	(145)
Restricted stock awards (in shares)		145
Exercise of employee stock options	3,418	182	3,236
Exercise of employee stock options (in shares)	188	182
Stock option and restricted stock award compensation expense	6,813		6,813
Ending Balance at Mar. 31, 2013	$ 2,108,829	$ 65,779	$ 170,444	$ 1,874,791	$ (2,185)
Ending Balance (in shares) at Mar. 31, 2013		65,779