Supplemental Cash Flow Information - Operating assets and liabilities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Components of operating assets and liabilities
Decrease (increase) in restricted cash	$ 32	$ 342
Decrease (increase) in accounts receivable	40,535	56,863
Decrease (increase) in receivable from affiliates	2,237	1,663
Decrease (increase) in inventories	4,834	(25,857)
Decrease (increase) in derivatives and margin deposits	3,914	(2,356)
Decrease (increase) in other current assets	1,582	2,280
Decrease (increase) in other assets	12	(628)
Increase (decrease) in accounts payable and accrued liabilities	(55,581)	(51,435)
Increase (decrease) in payable to affiliates	(1,626)	2,728
Increase (decrease) in payables to pre-petition creditors	0	(2)
Increase (decrease) in other noncurrent liabilities	(511)	95
Total changes in operating assets and liabilities	$ (4,572)	$ (16,307)