Income Taxes (Narrative) (Details) (USD $)	3 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Sep. 30, 2012
Income Tax Contingency [Line Items]
Income tax expense related to discontinued operations				$ 27,479,000
Income tax effect, increase (decrease) to shareholders' equity		715,000	16,000
Valuation allowance recorded during the period	796,300,000	802,771,000	(31,844,000)	(320,377,000)
Deferred tax assets expected to be realized	806,400,000	806,400,000
Valuation allowance	18,658,000	18,658,000	821,429,000
Discretionary bulk sale of distressed assets, pre-tax chagre	157,000,000
Asset ratio	38.07%	38.07%	62.51%		50.65%
Consolidated classified asset ratio	44.83%	44.83%	70.27%		58.65%
Net deferred income taxes	806,406,000	806,406,000	2,138,000
Deferred tax assets, not subject to expiration	189,600,000	189,600,000
Tax credit carryforward	44,563,000	44,563,000	44,170,000
Other tax credits	46,536,000	46,536,000	46,779,000
Unrecognized tax benefits, income tax penalties and interest accrued	163,000	163,000	1,500,000
Unrecognized tax benefits that would impact effective tax rate	834,000	834,000	4,800,000
Unrecognized tax benefits, income tax penalties and interest accrued that would impact effective tax rate	106,000	106,000	943,000
Approximate range of uncertain income tax positions expected to be settled or resolved during the next 12 months, minimum	358,000	358,000
2018 - 2032 [Member]
Income Tax Contingency [Line Items]
Deferred tax assets, subject to expiration	71,200,000	71,200,000
2013 - 2032 [Member]
Income Tax Contingency [Line Items]
Deferred tax assets, subject to expiration	25,500,000	25,500,000
2028 - 2032 [Member]
Income Tax Contingency [Line Items]
Deferred tax assets, subject to expiration	519,800,000	519,800,000
Federal [Member]
Income Tax Contingency [Line Items]
Alternative minimum tax credits	$ 19,063,000	$ 19,063,000