Consolidated Statements of Income (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Revenues	$ 139,253	$ 112,384
Costs and expenses:
Cost of goods sold	98,299	88,975
Selling, general and administrative expenses	13,596	10,890
Environmental remediation charge	750	0
Total costs and expenses	112,645	99,865
Operating income	26,608	12,519
Interest expense, net	(6,336)	(6,486)
Income before income taxes	20,272	6,033
Income tax provision	(4,785)	(982)
Net income	$ 15,487	$ 5,051
Net income per share:
Basic (in dollars per share)	$ 0.38	$ 0.13
Diluted (in dollars per share)	$ 0.38	$ 0.13
Distributions per share (in dollars per share)	$ 0.31	$ 0.31
Weighted-average shares outstanding (in thousands):
Basic (in shares)	40,435,608	40,261,149
Diluted (in shares)	40,612,974	40,364,992