Statements Of Comprehensive Operations (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Net income	$ 52,476	$ 50,565	$ 87,187	$ 87,392	$ 88,378	$ 92,211
Unrecognized pension and postretirement benefit costs:
Net gain (loss) arising during period	0	0	19,700	0	102,664	(2,109)
Prior service benefit	0	0	0	0	97	0
Reclassification adjustments included in net income for amortization of:
Prior service benefit	(2,065)	(1,369)	(5,594)	(4,169)	(6,985)	(5,610)
Net loss	1,615	2,903	4,567	8,323	6,716	11,316
Net unrealized gains/losses on marketable securities:
Net holding gains arising during period	897	4,300	7,965	8,861	16,803	6,802
Reclassification adjustments for net gains included in net income	(824)	(199)	(3,791)	(287)	(4,057)	(161)
Net losses on cash flow hedges:
Reclassification adjustment for interest expense included in net income	110	104	326	306	431	405
Total other comprehensive income (loss) before income taxes	(267)	5,739	23,173	13,034	115,669	10,643
Income tax benefit (expense) related to items of other comprehensive income (loss):
Unrecognized pension and postretirement benefit costs	171	(469)	(7,161)	(1,550)	(39,177)	(1,327)
Net unrealized gains on marketable securities	(31)	(796)	(889)	(1,433)	(2,556)	(1,300)
Losses on cash flow hedges	(42)	(39)	(174)	(129)	(213)	(143)
Total income tax benefit (expense)	98	(1,304)	(8,224)	(3,112)	(41,946)	(2,770)
Other comprehensive income (loss), net of tax	(169)	4,435	14,949	9,922	73,723	7,873
Comprehensive income	$ 52,307	$ 55,000	$ 102,136	$ 97,314	$ 162,101	$ 100,084