FAIR VALUE MEASUREMENTS (TABLES)

9 Months Ended

Sep. 30, 2012

Fair Value, Measurement Inputs, Disclosure [Table Text Block]

Fair values of financial instruments on the consolidated balance sheet (in millions):



September 30, 2012	Level 1		Level 2			Total

Assets
Marketable securities
U.S. government and agency securities	$	332.0	$	—		$	332.0
Foreign government bonds	—		45.5			45.5
Asset-back securities	—		102.0			102.0
Mortgage-back securities	—		119.3			119.3
Corporate notes and bonds	—		539.9			539.9
Municipal securities	—		19.4			19.4
Derivative instruments
Fuel hedge contracts	—		78.5			78.5

Liabilities
Derivative instruments
Interest rate swap agreements	—		(34.1		)	(34.1		)



December 31, 2011	Level 1		Level 2			Total

Assets
Marketable securities
U.S. government and agency securities	$	295.9	$	—		$	295.9
Foreign government bonds	—		25.4			25.4
Asset-back securities	—		58.0			58.0
Mortgage-back securities	—		124.9			124.9
Corporate notes and bonds	—		522.6			522.6
Municipal securities	—		11.9			11.9
Derivative instruments
Fuel hedge contracts	—		116.9			116.9

Liabilities
Derivative instruments
Fuel hedge contracts	—		(10.3		)	(10.3		)
Interest rate swap agreements	—		(28.8		)	(28.8		)

Fair Value, by Balance Sheet Grouping [Table Text Block]

Fixed-rate debt that is not carried at fair value on the consolidated balance sheet and the estimated fair value of long-term fixed-rate debt (in millions):



	September 30, 2012		December 31, 2011
Carrying amount	$	864.4	$	1,002.5
Fair value	950.0		1,075.8

- Definition

Tabular disclosure of the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments, assets, and liabilities. Such certain disclosures about the financial instruments, assets, and liabilities include: (1) the fair value of the required items together with their carrying amounts (as appropriate) and (2) the methodology and assumptions used in developing such estimates of fair value.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 107

-Paragraph 14

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 107

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+ Details

- Definition

The entire disclosure of the fair value measurement of assets and liabilities, which includes financial instruments measured at fair value that are classified in shareholders' equity, which may be measured on a recurring or nonrecurring basis.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

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-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19279-110258

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 157

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

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-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 157

-Paragraph 32

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 107

-Paragraph 10

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 157

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-Footnote 4

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