Leases (Details 1) (Charter Out [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
2013	$ 268,174
2014	221,089
2015	91,589
2016	28,783
2017	22,347
Thereafter	52,085
Net minimum lease payments	$ 684,067
Operating Days	14340 days
One Year From Balance Sheet [Member]
Operating Days	6901 days
More Than One and Within Two Years From Balance Sheet [Member]
Operating Days	4646 days
More Than Two and Within Three Years From Balance Sheet [Member]
Operating Days	1539 days
More Than Three and Within Four Years From Balance Sheet [Member]
Operating Days	373 days
More Than Four and Within Five Years From Balance Sheet [Member]
Operating Days	269 days
More Than Five Years From Balance Sheet and Thereafter [Member]
Operating Days	612 days