Share-Based Payment Arrangements (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended						9 Months Ended	12 Months Ended			24 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Sep. 30, 2011	Dec. 31, 2012	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures (in Shares)								900,000
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period								5 years
Share-based Compensation					$ 59	$ 179		$ 180	$ 432	$ (219)
Income Tax Expense (Benefit)	3,921	3,516	7,712	4,241	9,766	636		19,390	(17,123)	(24,388)
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	39							39
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life							146 days		10 years
Employee Service Share-based Compensation, Unrecognized Compensation Costs on Nonvested Awards (Deprecated 2011-01-31)	174							174
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value					204				678		912
Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number (in Shares)	529,104							529,104
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number (in Shares)	225,000							225,000
Four Abandoned Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number (in Shares)	113,293							113,293
Share-based payments [Member]
Income Tax Expense (Benefit)									100	(100)
Maximum [Member]
Income Tax Expense (Benefit)					$ 100			$ (100)