Fair Value Measurements (Assets Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Level 3), Reconciliation) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012
Fair Value Measurements [Abstract]
Balance at beginning of period	$ (115)	$ 182,119
Total gains or losses (realized/unrealized): Included in earnings	(14,037)	216,857
Total gains or losses (realized/unrealized): Included in other comprehensive income		(178,847)
Purchases, issuances, and settlements:
Purchases
Issuances
Settlements	(4,772)	(220,244)
Transfers into/out of Level 3
Balance at end of period	(18,924)	(115)
Change in unrealized gains included in earnings relating to derivatives still held as of December 31	$ (18,809)	$ (3,362)

Amount of unrealized (holding) gain (loss) which is included in the statement of income (or changes in net assets) related to those assets still held at the reporting date for which fair value is measured on a recurring basis using significant unobservable inputs (Level 3).

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

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Amount of gain (loss) recognized in the income statement for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of gain (loss) recognized in other comprehensive income (loss) for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of issuances of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of transfer of financial instrument classified as an asset into (out of) level 3 of the fair value hierarchy.

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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