Accrued and Other Current Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Schedule of accrued liabilities
Deferred revenue	$ 76,410
Salaries and wages	15,920	8,699
Incentive compensation	6,253	3,029
Interest	5,649	5,877
Vacation payable	4,871	4,305
Group medical	1,845	1,695
Transportations tax	1,545	1,448
Operating lease	862	880
Workers compensation	1,137	678
Other	2,670	2,440
Total accrued liabilities	$ 117,162	$ 29,051