Accounts Receivable Securitization (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accounts Receivable Securitization [Abstract]
Proceeds from accounts receivable securitization program	$ 60,000
Accounts receivable securitization program	99,200	$ 56,600
Fair value of the deferred purchase price receivable	$ 39,200	$ 16,600