Accounts Receivable - Schedule of Accounts Receivable (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	$ 338,601	$ 275,691
Allowance for doubtful accounts	(1,033)	(708)
Reserve for cash-basis customers	(7,990)	(2,995)
Total accounts receivable reserves	(9,023)	(3,703)
Accounts receivable, net	329,578	271,988
Trade Accounts Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	222,531	175,391
Unbilled Accounts Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	$ 116,070	$ 100,300