Financial Instruments and Risk Management (Offsetting Assets and Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross Amounts Recognized	$ 44,215	$ 149,504
Gross Amounts Offset in the Balance Sheets	(21,313)	(44,135)
Net Amount Presented in the Balance Sheets	22,902	105,369
Financial Instruments	0	0
Cash Collateral Received	0	0
Net Amount	22,902	105,369
Gross Amounts Recognized	51,615	56,328
Gross Amounts Offset in the Balance Sheets	(21,313)	(44,135)
Net Amount Presented in the Balance Sheets	30,302	12,193
Financial Instruments	0	0
Cash Collateral Received	0	0
Net Amount	$ 30,302	$ 12,193