Accounts and Notes Payable (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Accounts payable—third parties	$ 529,388	$ 474,017
Accounts payable to affiliates	12,544	20,726
Notes payable to banks	1,189	1,516
Accounts payable	$ 543,121	$ 496,259