Comprehensive Income (Components Of Comprehensive Income) (Details) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Comprehensive Income (Loss) [Line Items]
Net earnings	$ 25,599	$ 18,080	$ 41,744	$ 31,018
Amortization of prior service credit included in net periodic cost, net of tax of $(765), $(757), $(2,297) and $(2,270)	(1,198)	(1,183)	(3,592)	(3,550)
Amortization of actuarial loss included in net periodic cost, net of tax of $1,354, $1,248, $4,061 and $3,746	2,117	1,953	6,351	5,858
Curtailment gain, net of tax of $0, $0, $0, $(100)	0	0	0	(156)
Recognition of deferred taxes related to actuarial gain on OPEB obligations	0	(113)	0	5,580
Other comprehensive income, net of tax	919	657	2,759	7,732
Comprehensive income	26,518	18,737	44,503	38,750
Amortization of prior service credit included in net periodic cost, tax effect	(765)	(757)	(2,297)	(2,270)
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost, Tax	1,354	1,248	4,061	3,746
Curtailment gain, tax effect	0	0	0	(100)
Pension Plans [Member]
Comprehensive Income (Loss) [Line Items]
Other comprehensive income, net of tax	1,616	1,370	4,849	4,149
Other Postretirement Employee Benefits [Member]
Comprehensive Income (Loss) [Line Items]
Other comprehensive income, net of tax	$ (697)	$ (713)	$ (2,090)	$ 3,583