Concentrations - Additional Information (Detail) (Air Tran /Southwest [Member])	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011
Air Tran /Southwest [Member]
Entity Wide Portfolio Carrying Amount, Major Customer [Line Items]
Percentage of Revenue accounted	18.00%	21.00%

Percentage of revenue generated from a single external customer that accounts for 10 percent or more of an entity's revenues.

No definition available.

Name:	us-gaap_EntityWideRevenueMajorCustomerPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration