LONG-TERM DEBT - SCHEDULE OF LONG-TERM DEBT (DETAILS) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011 debtAgreements	Dec. 31, 2010	Dec. 31, 2009
Debt Instrument [Line Items]
Long-term Debt	$ 1,306.9	$ 1,534.2
Less current portion	207.9	221.2
Long-term debt, net of current portion	1,099.0	1,313.0
Weighted-average variable-interest rate	5.80%	6.00%
Weighted-average variable-interest rate	1.90%	1.80%
Scheduled debt payments	168.8
Number of Debt Agreements	7
Debt Agreements, Number with Partial Debt Balance	4
Prepayment of debt balance	164.7
Proceeds from Issuance of Long-term Debt	106.5	0	275.0
Long-term Debt, by Maturity [Abstract]
2012	207.9
2013	165.9
2014	122.3
2015	118.9
2016	116.5
Thereafter	575.4
Long-term Debt	1,306.9	1,534.2
Q400 [Member]
Debt Instrument [Line Items]
Proceeds from Issuance of Long-term Debt	106.5
Number of Aircraft Delivered	6
Fixed-rate notes payable due through 2024 [Member]
Debt Instrument [Line Items]
Long-term Debt	1,002.5	1,233.6
Long-term Debt, by Maturity [Abstract]
Long-term Debt	1,002.5	1,233.6
Variable-rate notes payable due through 2024 [Member]
Debt Instrument [Line Items]
Long-term Debt	304.4	300.6
Long-term Debt, by Maturity [Abstract]
Long-term Debt	$ 304.4	$ 300.6

Debt Agreements, Number

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Debt Agreements, Number with Partial Debt Balance

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Number of Aircraft Delivered

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Prepaid long term debt

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Amount of the required periodic payments including both interest and principal payments.

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Including current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date. May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one year or beyond the normal operating cycle, if longer, and after deducting unamortized discount or premiums, if any.

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Total of the portions of the carrying amounts as of the balance sheet date of long-term debt, which may include notes payable, bonds payable, debentures, mortgage loans, and commercial paper, which are scheduled to be repaid within one year or the normal operating cycle, if longer, and after deducting unamortized discount or premiums, if any.

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Amount of long-term debt maturities after year five following the date of the latest balance sheet presented in the financial statements, which may include maturities of long-term debt, sinking fund requirements, and other securities redeemable at fixed of determinable prices and dates.

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Amount of long-term debt maturing within the next twelve months following the date of the latest balance sheet presented in the financial statements, which may include maturities of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates.

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Amount of long-term debt maturing in year five following the date of the latest balance sheet presented in the financial statements, which may include maturities of long-term debt, sinking fund requirements, and other securities redeemable at fixed of determinable prices and dates.

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Amount of long-term debt maturing in year four following the date of the latest balance sheet presented in the financial statements, which may include maturities of long-term debt, sinking fund requirements, and other securities redeemable at fixed of determinable prices and dates.

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Amount of long-term debt maturing in year three following the date of the latest balance sheet presented in the financial statements, which may include maturities of long-term debt, sinking fund requirements, and other securities redeemable at fixed of determinable prices and dates.

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Amount of long-term debt maturing in year two following the date of the latest balance sheet presented in the financial statements, which may include maturities of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates.

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Sum of the carrying values as of the balance sheet date of all long-term debt, which is debt initially having maturities due after one year from the balance sheet date or beyond the operating cycle, if longer, but excluding the portions thereof scheduled to be repaid within one year (current maturities) or the normal operating cycle, if longer, and after deducting unamortized discount or premiums, if any.

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The interest rate applicable to the portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a set, unchanging rate.

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The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer.

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