Accounts Receivable (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Accounts Receivable, Net [Abstract]
Trade customers	$ 1,111,563	$ 819,739
Affiliates	7,601	7,982
Allowance for doubtful accounts	(21,961)	(17,991)
Accounts receivable from trade customers, net	1,097,203	809,730
Federal and state taxes	16,657	90,414
Other	29,119	38,599
Accounts receivable, net	$ 1,142,979	$ 938,743