Description of the Business and Summary of Significant Accounting Policies (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 M segment	Dec. 31, 2010
Basis of Presentation and Description of the Business
Number of operating segments	3
Cash and Cash Equivalents
Maximum term of original maturity to classify instruments as cash and cash equivalents (in months)	3
Accounts Receivable and Allowance for Doubtful Accounts
Accounts receivable	$ 137,084	$ 135,962
Unbilled accounts receivable	50,165	44,392
Allowance for doubtful accounts	(4,782)	(2,175)
Accounts receivable, net	$ 182,467	$ 178,179