- Summary of Changes in Accumulated Other Comprehensive Loss for Pension Plan Items (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive loss beginning balance	$ (7,517)	$ (8,652)
Other comprehensive income before reclassifications	(736)	0
Amounts reclassified from accumulated other comprehensive loss	476	97
Total other comprehensive income, net of tax	(260)	97
Accumulated other comprehensive loss ending balance	(7,777)	(8,555)
Investment income, net	274	107
Total before tax	509,904	(2,468)
Income tax benefit	(106,905)	0
Net income (loss)	402,989	(2,480)
Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Net income (loss)	476	97
Defined Benefit Pension Items
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive loss beginning balance	(5,392)	(8,652)
Other comprehensive income before reclassifications	(252)	0
Amounts reclassified from accumulated other comprehensive loss	229	97
Total other comprehensive income, net of tax	(23)	97
Accumulated other comprehensive loss ending balance	(5,415)	(8,555)
Defined Benefit Pension Items | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Amortization of loss	132	97
Settlement cost	240	0
Total before tax	372	97
Income tax benefit	143	0
Net income (loss)	229	97
Unrealized Gains and Losses on Available-for-Sale Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive loss beginning balance	(2,125)	0
Other comprehensive income before reclassifications	(484)	0
Amounts reclassified from accumulated other comprehensive loss	247	0
Total other comprehensive income, net of tax	(237)	0
Accumulated other comprehensive loss ending balance	(2,362)	0
Unrealized Gains and Losses on Available-for-Sale Securities | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Investment income, net	401	0
Income tax benefit	154	0
Net income (loss)	$ 247	$ 0