Accrued Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Accrued Liabilities, Current [Abstract]
Compensation and benefits	$ 40,132	$ 45,418
Customer advances	389	1,077
Deferred revenue	27,668	18,916
Taxes, other than income	11,015	9,749
Liabilities assumed in business combinations	2,069	6,132
Accrued contract costs	11,663	11,461
Accrued interest	14,706	8,694
Other	51,375	43,234
Total Accrued Liabilities	$ 159,017	$ 144,681