Carrying Values of the Major Classes of Assets Held for Sale Included in Condensed Consolidated Balance Sheets (Detail) (USD $) In Thousands	Jun. 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	$ 13,875	$ 10,161
Total long-term assets held for sale	78,110	77,150
Total assets held for sale	91,985	87,311
Charter Fleet Business
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash	1,968	1,426
Accounts receivable - net	8,357	5,253
Other assets	3,550	3,482
Total current assets held for sale	13,875	10,161
Property, plant and equipment - net	69,401	68,595
Other assets	8,709	8,555
Total long-term assets held for sale	78,110	77,150
Total assets held for sale	91,985	87,311
Accounts payable and accrued liabilities	8,372	8,748
Other liabilities	14,540	12,154
Total liabilities associated with assets held for sale	$ 22,912	$ 20,902