Share-Based Compensation (Narrative) (Detail) (USD $)	0 Months Ended	3 Months Ended		12 Months Ended	3 Months Ended										12 Months Ended		3 Months Ended		1 Months Ended		3 Months Ended								1 Months Ended
	Dec. 08, 2010	Sep. 30, 2012 D Y	Sep. 30, 2011 Y	Jun. 30, 2012	Sep. 30, 2012 Restricted Stock Units With Earning Per Share Performance Conditions [Member]	Sep. 30, 2011 Restricted Stock Units With Earning Per Share Performance Conditions [Member]	Sep. 30, 2012 Restricted Stock Units With Return On Invested Capital Performance Conditions [Member]	Sep. 30, 2012 Restricted Stock Units With Market Conditions [Member]	Sep. 30, 2011 Restricted Stock Units With Market Conditions [Member]	Sep. 30, 2012 Monte Carlo Simulation [Member]	Sep. 30, 2011 Monte Carlo Simulation [Member]	Sep. 30, 2012 Restricted Stock [Member]	Sep. 30, 2012 2012 Plan [Member]	Sep. 30, 2011 2012 Plan [Member]	Jun. 30, 2012 2012 Plan [Member]	Dec. 07, 2011 2012 Plan [Member]	Sep. 30, 2012 2012 Plan [Member] Full Value Grant [Member]	Sep. 30, 2012 2012 Plan [Member] Common Stock [Member]	Sep. 30, 2012 2012 Plan [Member] Restricted Stock Units [Member]	Jun. 30, 2012 2012 Plan [Member] Restricted Stock Units [Member]	Sep. 30, 2012 2012 Plan [Member] Restricted Stock Units [Member]	Sep. 30, 2012 2012 Plan [Member] Stock Appreciation Rights [Member]	Sep. 30, 2012 2002 Plan [Member]	Sep. 30, 2011 2002 Plan [Member]	Sep. 30, 2012 2002 Plan [Member] Common Stock [Member]	Sep. 30, 2011 2002 Plan [Member] Common Stock [Member]	Sep. 30, 2012 2002 Plan [Member] Restricted Stock Units [Member] Y	Sep. 30, 2011 2002 Plan [Member] Restricted Stock Units [Member] Y	Sep. 30, 2008 Outside 2002 Plan [Member] Restricted Stock Units [Member]	Jan. 31, 2008 Outside 2002 Plan [Member] Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant													3,249,102			4,400,000
Number of stock options, common stock and restricted stock units granted		458,675																458,675			526,817				0	445,967	0	618,919
Stock option and Incentive Plan, maturity date													Dec. 07, 2021
Number of awards for reduction of shares available for grant under 2012 Plan													1
Reduction in shares available for grant for one award under the plan																	1.71
Stock appreciation rights																						6,803
Number of shares available for grant of stock options, stock appreciation rights, restricted stock and restricted stock units	1,100,000
Grant of stock options stock appreciation rights, restricted stock and restricted stock units not to exceed for shares of common stock	7,860,000
Share-based compensation		$ 4,867,000	$ 2,541,000
Total income tax benefit recognized		1,300,000	700,000
Weighted-average grant-date fair value of options granted		$ 16.89	$ 13.18
Total intrinsic value of options exercised		5,500,000	100,000
Extended vesting period after employee termination, days		90
Total unrecognized compensation cost		40,400,000										0
Weighted average recognition period, years		1 year 10 months 24 days										0 years
Shares, Outstanding												0
Restricted stock units granted					97,733	118,546	97,733	97,733	118,546										869	1,150							232,749	263,281	28,344	34,608
Cliff vesting period, in years		3	3
Compensation expenses recognized period (years)																							3 years	3 years
Restricted stock units, grant date fair value										3,700,000	3,300,000
Restricted Stock Units vesting period																											3	3
Number of restricted stock units settled		1,608	1,608										0	0
Cash-settled restricted stock units, outstanding		0		1,608									2,019		1,150
Restricted stock units settled cost		100,000	100,000
Aggregate intrinsic value of equity classified restricted stock		$ 85,300,000
Cash-settled stock appreciation rights		6,803
Stock appreciation rights exercised		2,544
Stock appreciation rights outstanding		14,249
Stock appreciation rights exercisable		788