Lease Commitments (Details) (USD $)	12 Months Ended
	Dec. 31, 2011 Square_feet	Dec. 31, 2010	Dec. 31, 2009
Operating Leases, Future Minimum Payments Due [Abstract]
2012	$ 17,403,000
2013	11,502,000
2014	7,722,000
2015	4,456,000
2016	3,559,000
Thereafter	12,405,000
Total	57,047,000
Square footage of sublet office space	233,000
Square footage of remaining office space available for sublease	50,000
Operating leases, rent expense, net	22,500,000	16,900,000	10,700,000
Operating leases, future minimum payments due, future minimum sublease rentals, current	3,000,000
Operating leases, future minimum payments due, future minimum sublease rentals, in two years	900,000
Operating leases, future minimum payments due, future minimum Sublease Rentals, In Three Years	$ 700,000
Minimum [Member] | Computers, telephone systems, automobiles, and office equipment [Member]
Operating Leased Assets [Line Items]
Term of operating lease (in years)	12 months
Minimum [Member] | Office space [Member]
Operating Leased Assets [Line Items]
Term of operating lease (in years)	1 year
Maximum [Member] | Computers, telephone systems, automobiles, and office equipment [Member]
Operating Leased Assets [Line Items]
Term of operating lease (in years)	48 months
Maximum [Member] | Office space [Member]
Operating Leased Assets [Line Items]
Term of operating lease (in years)	20 years
United States and Latin America [Member]
Operating Leased Assets [Line Items]
Operating leases, number of properties	15
Europe, Asia, Australia, Japan and the CoE facilities in Bangalore and Hyderabad, India [Member]
Operating Leased Assets [Line Items]
Operating leases, number of properties	23