Summary of Financial Statement Preparation and Significant Accounting Policies (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Line Items]
Capitalized interest	$ 0.7	$ 0.7
Other liabilities for self-insured reserves	$ 30.7		$ 31.6
Minimum [Member] | Support equipment [Member]
Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life	5 years
Minimum [Member] | Vehicles and other equipment [Member]
Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life	3 years
Maximum [Member] | Support equipment [Member]
Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life	10 years
Maximum [Member] | Vehicles and other equipment [Member]
Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life	8 years
DC-8 combi aircraft and flight equipment [Member] | Aircraft and Flight Equipment [Member]
Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life	1 year
Boeing 767 and 757 aircraft and flight equipment [Member] | Minimum [Member] | Aircraft and Flight Equipment [Member]
Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life	10 years
Boeing 767 and 757 aircraft and flight equipment [Member] | Maximum [Member] | Aircraft and Flight Equipment [Member]
Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life	20 years