Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Allowance for doubtful accounts of trade accounts receivable	$ 3,470
Accumulated depreciation of vessels, equipment, and other fixed assets	$ 4,392
Preferred stock, par value (in dollars per share)	$ 0.01
Preferred stock, shares authorized (in shares)	5,000,000
Preferred stock, shares issued (in shares)	0
Common stock, par value (in dollars per share)	$ 0.01
Common stock, shares authorized (in shares)	25,000,000
Common stock, shares issued (in shares)	7,043,000
Common stock, shares outstanding (in shares)	7,042,000
Predecessor [Member]
Allowance for doubtful accounts of trade accounts receivable		$ 2,482
Accumulated depreciation of vessels, equipment, and other fixed assets		$ 468,817
Preferred stock, par value (in dollars per share)		$ 0.01
Preferred stock, shares authorized (in shares)		2,000,000
Preferred stock, shares issued (in shares)		0
Predecessor [Member] | Common Class A [Member]
Common stock, par value (in dollars per share)		$ 0.01
Common stock, shares authorized (in shares)		60,000,000
Common stock, shares issued (in shares)		29,104,000
Common stock, shares outstanding (in shares)		27,122,000
Predecessor [Member] | Common Class B [Member]
Common stock, par value (in dollars per share)		$ 0.01
Common stock, shares authorized (in shares)		60,000,000
Common stock, shares issued (in shares)		0