Accrued Expenses (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Summary of accrued expenses
Accrued multi-client data library acquisition costs	$ 47,678	$ 26,871
Compensation, including compensation-related taxes and commissions	28,993	19,398
Deferred income tax liability	20,556	5,695
Accrued legal contingency	10,000	0
Income tax payable	8,348	1,211
Other	8,520	8,209
Total accrued expenses	$ 124,095	$ 61,384