Reconciliation of Company's Fuel Call Options (Detail) (Fuel call options, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2010
Fuel call options
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning Balance	$ 9,998
Total gains or losses (realized /unrealized) Included in other (expense) income	(2,824)
Purchases	24,539
Transfers in and/or out of Level 3	(31,713)
The amount of total gains or losses for the period included in other (expense) income attributable to the change in unrealized gains or losses relating to assets still held at the reporting date	$ (2,824)