Comprehensive Income (Loss) (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Amounts included in AOCL
Balance, Beginning			$ (3,480)
Amounts reclassified into earnings			169	848
Changes in fair value			(2,555)	819
Balance, Ending	(5,866)		(5,866)
Interest Rate Swap [Member]
Amounts included in AOCL
Balance, Beginning			(5,652)
Amounts reclassified into earnings	847	985	1,554	2,142
Changes in fair value	(2,350)	(1,655)	(2,972)	(1,614)
Balance, Ending	(7,070)		(7,070)
Fuel Hedges [Member]
Amounts included in AOCL
Balance, Beginning			2,172
Amounts reclassified into earnings	(685)	(792)	(1,385)	(1,294)
Changes in fair value	(496)	(449)	417	2,433
Balance, Ending	$ 1,204		$ 1,204

Accumulated change, net of tax, in accumulated gains and losses from derivative instruments designated and qualifying as the effective portion of cash flow hedges. Includes an entity's share of an equity investee's Increase or Decrease in deferred hedging gains or losses.

+ References+ Details

Net of tax amount of the income statement impact of the reclassification adjustment of accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges realized in net income. Also includes reclassification adjustments of an entity's share of an equity investee's deferred hedging gain (loss) realized in net income.

+ References

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Reference 6: http://www.xbrl.org/2003/role/presentationRef

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+ Details

- Definition

Net of tax amount, before reclassification adjustments, of the change in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges. Also includes an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

+ References

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+ Details