Description of the Business and Summary of Significant Accounting Policies (Details) (USD $)	12 Months Ended
	Dec. 31, 2012 Segment	Dec. 31, 2011
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 years
Restricted Cash
Restricted cash	$ 30,398
Amounts held in escrow for investment in consortium	28,960
Investment in consortium, percentage	16.50%
Concessions period	12 years
Accounts Receivable and Allowance for Doubtful Accounts
Accounts receivable	178,572,000	137,084,000
Unbilled accounts receivable	42,525,000	50,165,000
Allowance for doubtful accounts	(10,952,000)	(4,782,000)
Accounts receivable, net	$ 210,145,000	$ 182,467,000