Consolidated Statements of Stockholders' Equity (Deficit) (USD $) In Thousands, unless otherwise specified	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Comprehensive Income
Balance at Sep. 30, 2009	$ (615,451)	$ 1,819	$ 635,519	$ (1,236,858)	$ (33)	$ (15,898)
Balance (in shares) at Sep. 30, 2009		181,858
Increase (Decrease) in Stockholders' Equity
Net earnings	143,828			143,828			143,828
Realized gains (losses) on interest rate swaps, net of income taxes of $2,503, $3,523 and $64 in 2012, 2011 and 2010, respectively	(101)					(101)	(101)
Foreign currency translation, net of income taxes of $201 for the year 2012	(4,277)					(4,277)	(4,277)
Total comprehensive income	139,450						139,450
Stock options subject to redemption	854		854
Share-based compensation	12,818	1	12,817
Share-based compensation (in shares)		88
Repurchases of common stock	(70)				(70)
Stock issued for stock options	1,127	2	1,125
Stock issued for stock options (in shares)		284
Balance at Sep. 30, 2010	(461,272)	1,822	650,315	(1,093,030)	(103)	(20,276)
Balance (in shares) at Sep. 30, 2010		182,230
Increase (Decrease) in Stockholders' Equity
Net earnings	213,725			213,725			213,725
Realized gains (losses) on interest rate swaps, net of income taxes of $2,503, $3,523 and $64 in 2012, 2011 and 2010, respectively	5,557					5,557	5,557
Foreign currency translation, net of income taxes of $201 for the year 2012	(7,952)					(7,952)	(7,952)
Total comprehensive income	211,330						211,330
Stock options subject to redemption	946		946
Share-based compensation	15,560	1	15,559
Share-based compensation (in shares)		96
Stock issued for stock options	14,454	18	14,436
Stock issued for stock options (in shares)		1,731
Balance at Sep. 30, 2011	(218,982)	1,841	681,256	(879,305)	(103)	(22,671)
Balance (in shares) at Sep. 30, 2011	184,057	184,057
Increase (Decrease) in Stockholders' Equity
Net earnings	233,064			233,064			233,064
Realized gains (losses) on interest rate swaps, net of income taxes of $2,503, $3,523 and $64 in 2012, 2011 and 2010, respectively	3,947					3,947	3,947
Foreign currency translation, net of income taxes of $201 for the year 2012	8,071					8,071	8,071
Total comprehensive income	245,082						245,082
Repurchase and cancellations of common stock	(200,000)	(76)	(200,027)		103
Repurchase and cancellations of common stock (in shares)		(7,567)
Share-based compensation	16,852	1	16,851
Share-based compensation (in shares)		126
Stock issued for stock options	41,963	36	41,927
Stock issued for stock options (in shares)		3,625
Balance at Sep. 30, 2012	$ (115,085)	$ 1,802	$ 540,007	$ (646,241)		$ (10,653)
Balance (in shares) at Sep. 30, 2012	180,241	180,241