Income Taxes (Tax Carryforwards) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Gross	$ 779,143	$ 868,963
Deferred Tax Assets, Valuation Allowance	(14,575)	(18,658)
Total deferred income tax assets	764,568	850,305
Alternative Minimum Tax Credit [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Gross	21,264
Deferred Tax Assets, Valuation Allowance	0
Total deferred income tax assets	21,264
Federal [Member] | Net Operating Loss [Member] | 2028 - 2032 [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Gross	445,675
Deferred Tax Assets, Valuation Allowance	0
Total deferred income tax assets	445,675
Federal [Member] | General Business Tax Credits [Member] | 2028 - 2033 [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Gross	9,297
Deferred Tax Assets, Valuation Allowance	0
Total deferred income tax assets	9,297
State [Member] | Net Operating Loss [Member] | 2028 - 2033 [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Gross	60,563
Deferred Tax Assets, Valuation Allowance	0
Total deferred income tax assets	60,563
State [Member] | Net Operating Loss [Member] | 2013 - 2017 [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Gross	37
Deferred Tax Assets, Valuation Allowance	0
Total deferred income tax assets	37
State [Member] | Net Operating Loss [Member] | 2018 - 2022 [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Gross	0
Deferred Tax Assets, Valuation Allowance	0
Total deferred income tax assets	0
State [Member] | Net Operating Loss [Member] | 2023 - 2027 [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Gross	4,074
Deferred Tax Assets, Valuation Allowance	0
Total deferred income tax assets	4,074
State [Member] | Other Credits [Member] | 2014 - 2017 [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Gross	12,307
Deferred Tax Assets, Valuation Allowance	(11,752)
Total deferred income tax assets	555
State [Member] | Other Credits [Member] | 2018 - 2023 [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Gross	2,899
Deferred Tax Assets, Valuation Allowance	(2,823)
Total deferred income tax assets	$ 76