Income Taxes (Narrative) (Details) (USD $)	3 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Contingency [Line Items]
Income tax effect, increase (decrease) to shareholders' equity		$ 317,000	$ 715,000
Valuation allowance recorded during the period	796,300,000	4,083,000	802,771,000	(31,844,000)
Deferred tax assets expected to be realized	744,600,000	744,600,000	806,400,000
Valuation allowance, amount reversed			802,800,000
Valuation allowance	14,575,000	14,575,000	18,658,000
Net deferred income taxes	744,646,000	744,646,000	806,406,000
Deferred tax assets, not subject to expiration	203,000,000	203,000,000
Tax credit carryforward	45,767,000	45,767,000	44,563,000
Other tax credits	48,852,000	48,852,000	27,990,000
Unrecognized tax benefits, income tax penalties and interest accrued	109,000	109,000	163,000
Unrecognized tax benefits that would impact effective tax rate	663,000	663,000	834,000
Unrecognized tax benefits, income tax penalties and interest accrued that would impact effective tax rate	71,000	71,000	106,000
Approximate range of uncertain income tax positions expected to be settled or resolved during the next 12 months, minimum	162,000	162,000
Through 2023 [Member]
Income Tax Contingency [Line Items]
Valuation allowance	14,600,000	14,600,000
2028 - 2032 [Member]
Income Tax Contingency [Line Items]
Deferred tax assets, subject to expiration	445,700,000	445,700,000
Through 2033 [Member]
Income Tax Contingency [Line Items]
Deferred tax assets, subject to expiration	64,700,000	64,700,000
Federal [Member]
Income Tax Contingency [Line Items]
Alternative minimum tax credits	21,300,000	21,300,000
Federal and State [Member] | Through 2033 [Member]
Income Tax Contingency [Line Items]
Deferred tax assets, subject to expiration	$ 24,500,000	$ 24,500,000