Retirement Plans (Projected Benefit Obligation) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Change in plan assets [Roll Forward]
Fair value of plan assets at end of year	$ 1,216,525	$ 1,253,666
Amounts recognized in the consolidated balance sheet [Abstract]
Pension and other postretirement benefits	(725,333)	(1,055,058)
Pension Benefits [Member]
Change in projected benefit obligation (PBO) [Roll Forward]
PBO at beginning of year	1,944,731	1,799,313
Service cost	47,651	43,688	38,879
Interest cost	75,812	78,027	84,228
Actuarial loss	(180,709)	196,304
Benefits paid	(54,151)	(172,601)
Settlements	(164,608)
PBO at end of year	1,668,726	1,944,731	1,799,313
Change in plan assets [Roll Forward]
Fair value of plan assets at beginning of year	1,253,666	1,257,990
Actual return on plan assets	119,328	139,679
Contributions to pension plan	62,290	28,598	76,700
Benefits paid	(54,151)	(172,601)
Settlements	(164,608)
Fair value of plan assets at end of year	1,216,525	1,253,666	1,257,990
Funded status	(452,201)	(691,065)
Amounts recognized in the consolidated balance sheet [Abstract]
Current liabilities	(100,205)	(60,386)
Pension and other postretirement benefits	(351,996)	(630,679)
Accumulated other comprehensive loss	411,432	697,874
Postretirement Benefits Other Than Pensions (OPEB) [Member]
Change in projected benefit obligation (PBO) [Roll Forward]
PBO at beginning of year	438,550	391,596
Service cost	12,533	10,812	8,958
Interest cost	17,241	17,842	17,722
Plan participants' contributions	4,293	4,059
Actuarial loss	(67,547)	30,958
Benefits paid	(19,447)	(15,974)
Plan change		743
PBO at end of year	385,623	438,550	391,596
Change in plan assets [Roll Forward]
Fair value of plan assets at beginning of year	5,055	5,101
Actual return on plan assets	(122)	466
Plan participant's contributions	4,293	4,059
Contributions to pension plan	12,528	11,403
Benefits paid	(19,447)	(15,974)
Fair value of plan assets at end of year	2,307	5,055	5,101
Funded status	(383,316)	(433,495)
Amounts recognized in the consolidated balance sheet [Abstract]
Current liabilities	(11,508)	(9,116)
Pension and other postretirement benefits	(371,808)	(424,379)
Accumulated other comprehensive loss	$ 5,230	$ 74,264