Note 4 - Prepaid Expenses and Other Current Assets (Detail) - Prepaid Expenses and Other Current Assets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Prepaid expenses and other current assets	$ 15,415	$ 13,466
Prepaid Tires [Member]
Prepaid expenses and other current assets	9,174	8,999
Prepaid Licenses, Permits and Tolls [Member]
Prepaid expenses and other current assets	1,951	2,114
Prepaid Insurance [Member]
Prepaid expenses and other current assets	1,649	1,409
Other Current Assets [Member]
Prepaid expenses and other current assets	$ 2,641	$ 944