Share-Based Payment Arrangements (Detail) - Stock Option Activity (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Sep. 30, 2010
Outstanding [Member]
Number of Shares	259,189	404,387	501,637	720,851
Weighted-Average Exercise Price ($) (in Dollars per share)	$ 22.30	$ 23.80	$ 24.11	$ 24.63
Weighted-Average Remaining Contractual Term (Years)	1 year 164 days
Aggregate Intrinsic Value ($000) (in Dollars)	$ 41
Granted [Member]
Number of Shares		0	0	0
Exercised [Member]
Number of Shares		0	0	0
Forfeited Or Expired [Member]
Number of Shares		(145,198)	(97,250)	(219,214)
Weighted-Average Exercise Price ($) (in Dollars per share)		$ 26.49	$ 25.43	$ 25.80
Exercisable [Member]
Number of Shares	241,896
Weighted-Average Exercise Price ($) (in Dollars per share)	$ 22.88
Weighted-Average Remaining Contractual Term (Years)	1 year 138 days
Aggregate Intrinsic Value ($000) (in Dollars)	$ 41