Business Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013 segment	Mar. 31, 2012	Dec. 31, 2012
Segment Reporting [Abstract]
Number of Reportable Segments	4
Segment Reporting Information [Line Items]
Assets held for sale	$ 1,251		$ 3,578
Operating Revenues	435,409	350,206
Intersegment Revenues Eliminations	(1,723)	(1,880)
Total revenues	433,686	348,326
Depreciation and amortization	11,893	9,953
Operating Income (loss) after eliminations	26,385	19,781
Capital Expenditures	14,715	31,035
Total Assets [Abstract]
Assets Excluding Held for Sale	1,036,365		1,012,996
Terminalling and storage [Member]
Segment Reporting Information [Line Items]
Operating Revenues	80,353	81,976
Intersegment Revenues Eliminations	(1,141)	(1,175)
Total revenues	79,212	80,801
Depreciation and amortization	7,096	4,976
Operating Income (loss) after eliminations	9,983	6,779
Capital Expenditures	14,049	24,324
Total Assets [Abstract]
Assets Excluding Held for Sale	384,759		376,330
Natural gas services [Member]
Segment Reporting Information [Line Items]
Operating Revenues	259,439	172,111
Intersegment Revenues Eliminations	0	0
Total revenues	259,439	172,111
Depreciation and amortization	292	143
Operating Income (loss) after eliminations	8,462	3,220
Capital Expenditures	115	14
Total Assets [Abstract]
Assets Excluding Held for Sale	314,330		331,064
Sulfur services [Member]
Segment Reporting Information [Line Items]
Operating Revenues	70,385	74,552
Intersegment Revenues Eliminations	0	0
Total revenues	70,385	74,552
Depreciation and amortization	1,966	1,793
Operating Income (loss) after eliminations	9,344	13,627
Capital Expenditures	201	989
Total Assets [Abstract]
Assets Excluding Held for Sale	172,267		155,639
Marine transportation [Member]
Segment Reporting Information [Line Items]
Operating Revenues	25,232	21,567
Intersegment Revenues Eliminations	(582)	(705)
Total revenues	24,650	20,862
Depreciation and amortization	2,539	3,041
Operating Income (loss) after eliminations	2,539	(1,427)
Capital Expenditures	350	5,708
Total Assets [Abstract]
Assets Excluding Held for Sale	165,009		149,963
Indirect selling, general and administrative [Member]
Segment Reporting Information [Line Items]
Operating Revenues	0	0
Intersegment Revenues Eliminations	0	0
Total revenues	0	0
Depreciation and amortization	0	0
Operating Income (loss) after eliminations	(3,943)	(2,418)
Capital Expenditures	$ 0	$ 0