Accumulated Other Comprehensive Income (Loss) (Reclassifications out of AOCI) (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended							12 Months Ended
	Mar. 31, 2014		Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013		Dec. 31, 2013	Dec. 31, 2012
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Interest expense	$ 8,820		$ 8,838	$ 9,221	$ 9,048	$ 8,960		$ 36,067	$ 35,944
Other income (expense), net	(133,273)		14,920	(8,110)	12,858	4,083		23,751	5,456
Amortization of net prior service credit included in net income	(102)					(437)
Amortization of net actuarial (gain) loss included in net income	(7,182)					2,317
Settlement gain included in net income	0					3,471
Income Before Tax	(208,633)		(74,486)	(83,839)	(78,785)	(38,032)		(275,142)	(125,748)
Provision for Income Taxes	77,400		24,100	29,900	31,700	15,800		101,500	73,400
Income Net of Tax	(131,233)		(50,386)	(53,939)	(47,085)	(22,232)		(173,642)	(52,348)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income Net of Tax	(3,773)					(1,174)
Unrealized Gain on Available-for-Sale Securities [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Other income (expense), net	785					(551)
Provision for Income Taxes	(314)					220
Income Net of Tax	471					(331)
Pension and Other Postretirement Plans [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Amortization of net prior service credit included in net income	(102)	[1]				(437)	[1]
Amortization of net actuarial (gain) loss included in net income	(7,182)	[1]				2,317	[1]
Settlement gain included in net income	0	[1]				(3,471)	[1]
Income Before Tax	(7,284)					(1,591)
Provision for Income Taxes	2,913					636
Income Net of Tax	(4,371)					(955)
Cash Flow Hedge [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Interest expense	212					186
Provision for Income Taxes	(85)					(74)
Income Net of Tax	$ 127					$ 112

[1] These accumulated other comprehensive income components are included in the computation of net periodic pension and postretirement plan cost (see Note 9).