Long-Term Debt (IKE Zone Act Senior Notes Due 2035) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended	1 Months Ended
	Dec. 31, 2014	Dec. 31, 2010	Dec. 31, 2013	Dec. 02, 2010
Debt Instrument [Line Items]
Stated interest rate	6.50%
Minimum debt amount guaranteed by subsidiaries	5,000
Ike Zone Six Point Five Percent Tax Exempt Revenue Bonds Due Twenty Thirty Five [Member]
Debt Instrument [Line Items]
Stated interest rate	6.50%		6.50%
Minimum debt amount guaranteed by subsidiaries	5,000
Ike Zone Six Point Five Percent Tax Exempt Revenue Bonds Due Twenty Thirty Five [Member] | Redeemed Prior To November 1, 2020 [Member]
Debt Instrument [Line Items]
Percentage of principal required if called	100.00%
Ike Zone Six Point Five Percent Tax Exempt Revenue Bonds Due Twenty Thirty Five [Member] | Redeemed On Or After November 1, 2020 [Member]
Debt Instrument [Line Items]
Percentage of principal required if called	100.00%
Emergency Economic Stabilization Act Of 2008 [Member] | Ike Zone Six Point Five Percent Tax Exempt Revenue Bonds Due Twenty Thirty Five [Member]
Debt Instrument [Line Items]
Senior notes, principal amount issued				$ 65,000
Stated interest rate				6.50%
Maturity date		Nov. 01, 2035