Schedule I Condensed Financial Information Parent - Equity methods investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income (Loss) from equity method investments	$ 3,747	$ 3,642	$ 3,783
Parent Company [Member]
Income (Loss) from equity method investments	6,575	(63,698)	47,534
Parent Company [Member] | Osg Bulk Ships Inc [Member]
Income (Loss) from equity method investments	(6,576)	(63,744)	47,482
Parent Company [Member] | Osg Financial Corporation [Member]
Income (Loss) from equity method investments	$ 1	$ 46	$ 52