Statements Of Comprehensive Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net income	$ 21,072	$ 30,096	$ 24,530	$ 34,711	$ 81,247	$ 86,467
Unrecognized pension and post-retirement benefit costs:
Net gain (loss) arising during period	0	0	0	19,700	(74,028)	102,664
Prior service benefit	0	0	0	0	34,200	97
Reclassification adjustments included in net income for amortization of:
Prior service benefit	(1,662)	(2,070)	(3,325)	(3,529)	(7,455)	(6,289)
Net loss	2,250	1,829	4,500	2,952	7,730	8,004
Net unrealized gains/losses on marketable securities:
Net holding gains (losses) arising during period	(1,563)	6,070	(549)	7,068	3,210	20,206
Reclassification adjustments for net (gains) losses included in net income	182	(102)	(3,563)	(2,967)	(7,946)	(3,432)
Net losses on cash flow hedges:
Reclassification adjustment for interest expense included in net income	116	109	230	216	452	425
Total other comprehensive income (loss) before income taxes	(677)	5,836	(2,707)	23,440	(43,837)	121,675
Income tax benefit (expense) related to items of other comprehensive income (loss):
Unrecognized pension and post-retirement benefit costs	(291)	90	(622)	(7,332)	14,761	(39,817)
Net unrealized losses (gains) on marketable securities	325	(1,215)	881	(858)	979	(3,321)
Losses on cash flow hedges	(43)	(40)	(115)	(132)	(197)	(210)
Total income tax benefit (expense)	(9)	(1,165)	144	(8,322)	15,543	(43,348)
Other comprehensive income (loss), net of tax	(686)	4,671	(2,563)	15,118	(28,294)	78,327
Comprehensive income	$ 20,386	$ 34,767	$ 21,967	$ 49,829	$ 52,953	$ 164,794