REVENUES BY CLIENT LOCATION (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 133,184	$ 103,800	$ 257,382	$ 198,183
Reimbursable expenses and other revenues [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,510	1,706	2,948	2,793
United States [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	59,746	48,565	117,196	94,604
United Kingdom [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	27,711	22,858	54,779	45,786
Russia [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	13,192	9,393	24,930	18,491
Switzerland [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	10,734	6,797	20,014	12,942
Canada [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	8,393	1,763	13,818	2,546
Germany [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	4,537	3,959	9,070	7,441
Ukraine [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	143	4,321	331	4,375
Kazakhstan [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	2,028	1,662	4,493	3,333
Sweden [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,349	1,017	2,604	2,472
Netherlands [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	2,384	868	4,770	1,658
Spain [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	609	377	1,241	722
Other Countries [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 848	$ 514	$ 1,188	$ 1,020