Accounts Receivable - Schedule of Accounts Receivable (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	$ 374,483	$ 387,763
Allowance for doubtful accounts	(1,189)	(906)
Reserve for cash-basis customers	(8,191)	(6,458)
Total accounts receivable reserves	(9,380)	(7,364)
Accounts receivable, net	365,103	380,399
Unbilled accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	106,674	124,878
Trade accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross accounts receivable	$ 267,809	$ 262,885