Accounts Receivable - Schedule of Accounts Receivable (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	$ 372,888	$ 387,763
Allowance for doubtful accounts	(1,391)	(906)
Reserve for cash-basis customers	(7,096)	(6,458)
Total accounts receivable reserves	(8,487)	(7,364)
Accounts receivable, net	364,401	380,399
Unbilled accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	108,243	124,878
Trade accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	$ 264,645	$ 262,885