Derivatives And Risk Management (Interest Rate Swap Agreements) (Detail) (USD $) In Thousands, unless otherwise specified		9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended
	May 30, 2012	Sep. 30, 2012 July 2012 [Member] Interest Rate Swap [Member]	Dec. 31, 2011 July 2012 [Member] Interest Rate Swap [Member] Derivative	Sep. 30, 2012 June 2013 [Member] Interest Rate Swap [Member] Derivative	Dec. 31, 2011 June 2013 [Member] Interest Rate Swap [Member] Derivative	Sep. 30, 2012 October Two Thousand Fourteen [Member] Interest Rate Swap [Member] Derivative	Dec. 31, 2011 October Two Thousand Fourteen [Member] Interest Rate Swap [Member]	Sep. 30, 2012 October Two Thousand Fifteen [Member] Interest Rate Swap [Member] Derivative	Dec. 31, 2011 October Two Thousand Fifteen [Member] Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Number of contracts			3	2	2	2		1
Notional amount	$ 75,000		$ 75,000	$ 85,000	$ 85,000	$ 50,000		$ 25,000
Mandatory cash settlement date		-	July 2012	June 2013	June 2013	October 2014	-	October 2015	-