Carrying Values of the Major Classes of Assets Held for Sale Included in Condensed Consolidated Balance Sheets (Detail) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total current assets held for sale	$ 20,630	$ 10,161
Total long-term assets held for sale	76,315	77,150
Total assets held for sale	96,945	87,311
Charter Fleet Business
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash	3,439	1,426
Accounts receivable - net	13,200	5,253
Other assets	3,991	3,482
Total current assets held for sale	20,630	10,161
Property, plant and equipment - net	67,247	68,595
Other assets	9,068	8,555
Total long-term assets held for sale	76,315	77,150
Total assets held for sale	96,945	87,311
Accounts payable and accrued liabilities	7,830	8,748
Other liabilities	15,458	12,154
Total liabilities associated with assets held for sale	$ 23,288	$ 20,902