Share-Based Compensation - Additional Information (Detail)	3 Months Ended
	Dec. 31, 2012
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Share-based compensation number of plans maintained	3
2002 directors stock option plan
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Shares available for grant	0
2002 directors plan prior to September 30, 2007
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Options vested at the grant date	50.00%
Options vested at the grant date	50.00%
Expiration period, from grant date	10 years
2002 directors plan in November 2007
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Options vested at the grant date	50.00%
Expiration period, from grant date	10 years
Options vested on the one-year anniversary of the grant date	50.00%
2008 Stock Incentive Plan
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Expiration period, from grant date	10 years
Shares available for grant	238,483
Common stock authorized	800,000
Maximum shares of common stock able to be granted pursuant to awards of restricted stock and restricted stock units	400,000
Number of annual installments	3
2001 Stock Option Plan
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Options vested at the grant date	50.00%
Options vested at the grant date	50.00%
Expiration period, from grant date	10 years
Shares available for grant	0
Restricted Stock Awards And Units
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
RSU awards cliff-vest date	Sep. 30, 2014
RSU awards cliff-vest period	2 years