Commitments and Contingencies - Sale Leaseback Transactions Aircraft (Details) (Aircraft [Member], USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2012 aircraft
Aircraft [Member]
Sale Leaseback Transaction [Line Items]
Number of aircraft entered into sale and leaseback agreement	5
Sale leaseback transaction on aircraft, deferred gain (loss)	$ (4.9)
Sale leaseback transaction on aircraft, refund in pre-delivery deposits	$ 27.9

The amount of the gain recorded in connection with the transaction involving the sale of property to another party and the lease of the property back to the seller to be recognized in future periods.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 40

-Section 25

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6456126&loc=d3e49567-112750

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 13

-Paragraph 33

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

Name:	us-gaap_SaleLeasebackTransactionDeferredGainGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant