Other Postretirement Benefit Plans (Schedule Of Percentage Point Change In Assumed Health Care Cost Trend Rate Effecting Service And Interest Cost And Accumulated Postretirement Benefit Obligation) (Detail) (Other Postretirement Benefit Plans [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Other Postretirement Benefit Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Effect on service and interest components of net periodic cost, 1% Increase	$ 2
Effect on accumulated postretirement benefit obligation, 1% Increase	51
Effect on service and interest components of net periodic cost, 1% Decrease	(2)
Effect on accumulated postretirement benefit obligation, 1% Decrease	$ (47)