Compensation Programs (Schedule Of Performance-Based Stock Awards) (Detail) (USD $)	12 Months Ended					1 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2012 2008 [Member]	Dec. 31, 2012 2009 [Member]	Dec. 31, 2012 2010 [Member]	Dec. 31, 2012 2011 [Member]	Jul. 31, 2012 2012 [Member]	Dec. 31, 2012 2012 [Member]	Dec. 31, 2012 Performance-Based Stock Awards [Member]	Dec. 31, 2012 Performance-Based Stock Awards [Member] 2008 [Member]		Dec. 31, 2012 Performance-Based Stock Awards [Member] 2009 [Member]		Dec. 31, 2012 Performance-Based Stock Awards [Member] 2010 [Member]	Dec. 31, 2012 Performance-Based Stock Awards [Member] 2011 [Member]	Dec. 31, 2012 Performance-Based Stock Awards [Member] 2012 [Member]	Dec. 31, 2012 Remaining Shares With Initial Measurement Periods 2013 [Member] Performance-Based Stock Awards [Member] 2008 [Member]	Dec. 31, 2012 Remaining Shares With Initial Measurement Periods 2013 [Member] Performance-Based Stock Awards [Member] 2009 [Member]	Dec. 31, 2012 Remaining Shares With Initial Measurement Periods 2013 [Member] Performance-Based Stock Awards [Member] 2010 [Member]	Dec. 31, 2012 Remaining Shares With Initial Measurement Periods 2013 [Member] Performance-Based Stock Awards [Member] 2011 [Member]	Dec. 31, 2012 Remaining Shares With Initial Measurement Periods 2013 [Member] Performance-Based Stock Awards [Member] 2012 [Member]	Dec. 31, 2012 Remaining Shares With Initial Measurement Periods 2014 [Member] Performance-Based Stock Awards [Member] 2008 [Member]	Dec. 31, 2012 Remaining Shares With Initial Measurement Periods 2014 [Member] Performance-Based Stock Awards [Member] 2009 [Member]	Dec. 31, 2012 Remaining Shares With Initial Measurement Periods 2014 [Member] Performance-Based Stock Awards [Member] 2010 [Member]	Dec. 31, 2012 Remaining Shares With Initial Measurement Periods 2014 [Member] Performance-Based Stock Awards [Member] 2011 [Member]	Dec. 31, 2012 Remaining Shares With Initial Measurement Periods 2014 [Member] Performance-Based Stock Awards [Member] 2012 [Member]	Dec. 31, 2012 Remaining Shares With Initial Measurement Periods 2015 [Member] Performance-Based Stock Awards [Member] 2008 [Member]	Dec. 31, 2012 Remaining Shares With Initial Measurement Periods 2015 [Member] Performance-Based Stock Awards [Member] 2009 [Member]	Dec. 31, 2012 Remaining Shares With Initial Measurement Periods 2015 [Member] Performance-Based Stock Awards [Member] 2010 [Member]	Dec. 31, 2012 Remaining Shares With Initial Measurement Periods 2015 [Member] Performance-Based Stock Awards [Member] 2011 [Member]	Dec. 31, 2012 Remaining Shares With Initial Measurement Periods 2015 [Member] Performance-Based Stock Awards [Member] 2012 [Member]	Dec. 31, 2012 Remaining Shares With Initial Measurement Periods 2016 [Member] Performance-Based Stock Awards [Member] 2008 [Member]	Dec. 31, 2012 Remaining Shares With Initial Measurement Periods 2016 [Member] Performance-Based Stock Awards [Member] 2009 [Member]	Dec. 31, 2012 Remaining Shares With Initial Measurement Periods 2016 [Member] Performance-Based Stock Awards [Member] 2010 [Member]	Dec. 31, 2012 Remaining Shares With Initial Measurement Periods 2016 [Member] Performance-Based Stock Awards [Member] 2011 [Member]	Dec. 31, 2012 Remaining Shares With Initial Measurement Periods 2016 [Member] Performance-Based Stock Awards [Member] 2012 [Member]	Dec. 31, 2012 Two Thousand and Eight Grants [Member] Performance-Based Stock Awards [Member]	Dec. 31, 2011 Two Thousand and Eight Grants [Member] Performance-Based Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Year of Grant									2008		2009		2010	2011	2012
Grant Date Fair Value Per Share	$ 11.99	$ 12.87	$ 11.39	$ 11.64	$ 13.23		$ 13.59		$ 10.18		$ 14.33		$ 12.44	$ 12.72	$ 11.67
Total Original Grants	654,000	225,000	225,000	60,000	72,000	72,000	72,000		140,658	[1]	110,917	[2]	128,766	132,490	145,399
Expiration date of grant	Jul. 01, 2015								Dec. 31, 2015		Dec. 31, 2016		Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2019
Remaining Shares Vesting in Period	114,097																55,035	64,087
Performance-based awards vested, shares								53,431															64,077	66,247					66,243	72,700					72,699	135,194	135,194
Percentage of performance based awards granted, actual								50.00%

[1] The performance criteria for the three-year measurement periods ending December 31, 2012 and 2011 were met resulting in the vesting of 135,194 shares associated with this grant.

[2] The performance criteria for the first three-year measurement period ending December 31, 2012 was met resulting in the vesting of 53,431 shares associated with the first 50% of this grant.