Quarterly Financial Information (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Information [Abstract]
Revenues	$ 70,978		$ 74,410		$ 76,752		$ 72,694		$ 76,169		$ 77,938		$ 74,897		$ 81,124		$ 294,834	$ 310,128	$ 243,496
Voyage Expenses	52,355	[1]	55,450	[1]	57,802	[1]	57,433	[1]	52,269	[1]	60,395	[1]	58,067	[1]	65,970	[1]	223,040	236,701	178,860
Operating Income (Loss)	(36,975)		1,074		1,660		(2,256)		6,048		1,959		1,404		306		(36,497)	9,717	23,971
Net (Loss) Income	$ (48,253)		$ (2,565)		$ (664)		$ (3,217)		$ 17,242		$ (2,222)		$ 1,859		$ 1,653		$ (54,699)	$ 18,532	$ 21,962
Basic and Diluted Earnings (Loss) Per Common Share:
Basic Earnings (Loss) Per Common Share: (in dollars per share)	$ (6.81)		$ (0.53)		$ (0.27)		$ (0.62)		$ 2.21		$ (0.46)		$ 0.17		$ 0.19		$ (8.23)	$ 2.11	$ 3.05
Diluted Earnings (Loss) Per Common Share: (in dollars per share)	$ (6.81)		$ (0.53)		$ (0.27)		$ (0.62)		$ 2.20		$ (0.46)		$ 0.17		$ 0.19		$ (8.23)	$ 2.10	$ 3.04

[1] Certain previously reported amounts have been reclassified out of voyage expense and into amortization and depreciation expense to conform to the 2014 presentation.