Supplemental Cash Flow Information (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Supplemental Cash Flow Information
Cash paid for interest, net of amounts capitalized	$ 43,262,000	$ 51,622,000
Cash paid (received) for income taxes, net	(149,000)	(183,000)
Supplemental schedule of non-cash investing and financing activities:
Amounts payable for property, plant and equipment(1)	276,046,000	553,370,000
Interest capitalized on construction in progress	5,556,000	5,936,000
Issuance of common units for vesting of share-based payment awards	12,044,000	7,720,000
Accrued property, plant and equipment	$ 157,100,000