Comprehensive Income (Accumulated Other Comprehensive Loss, Net of Tax) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning	$ (483,576)	$ (386,963)	$ (229,549)
Other comprehensive income before reclassifications	171,681	(113,453)	(163,236)
Amounts reclassified from accumulated other comprehensive loss	23,984	16,840	5,822
Recognition of net actuarial loss for pension settlement costs	27,381
Net current-period other comprehensive income (loss)	223,046	(96,613)	(157,414)
Balance, ending	(260,530)	(483,576)	(386,963)
Pension Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning	(697,874)	(575,163)	(349,264)
Other comprehensive income before reclassifications	205,341	(152,402)	(241,064)
Amounts reclassified from accumulated other comprehensive loss	36,938	29,691	15,165
Recognition of net actuarial loss for pension settlement costs	44,163
Net current-period other comprehensive income (loss)	286,442	(122,711)	(225,899)
Balance, ending	(411,432)	(697,874)	(575,163)
Postretirement Costs [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning	(74,264)	(41,811)	(13,369)
Other comprehensive income before reclassifications	67,289	(29,922)	(22,668)
Amounts reclassified from accumulated other comprehensive loss	1,745	(2,531)	(5,774)
Net current-period other comprehensive income (loss)	69,034	(32,453)	(28,442)
Balance, ending	(5,230)	(74,264)	(41,811)
Deferred Taxes On Pension And OPEB Costs [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning	288,712	230,161	132,752
Other comprehensive income before reclassifications	(100,951)	68,871	100,978
Amounts reclassified from accumulated other comprehensive loss	(14,699)	(10,320)	(3,569)
Recognition of net actuarial loss for pension settlement costs	(16,782)
Net current-period other comprehensive income (loss)	(132,432)	58,551	97,409
Balance, ending	156,280	288,712	230,161
All Other [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning	(150)	(150)	332
Other comprehensive income before reclassifications	2		(482)
Amounts reclassified from accumulated other comprehensive loss
Net current-period other comprehensive income (loss)	2		(482)
Balance, ending	$ (148)	$ (150)	$ (150)