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SEGMENT INFORMATION (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended	12 Months Ended	0 Months Ended	3 Months Ended						6 Months Ended		12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2014 segment	Jul. 09, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Jul. 09, 2014	Jul. 09, 2014	Dec. 31, 2013	Dec. 31, 2012
SEGMENT INFORMATION
Number of reportable segments				2us-gaap_NumberOfReportableSegments
Number of operating segments				2us-gaap_NumberOfOperatingSegments
Voyage revenue from external customers
Total consolidated voyage revenue from external customers			$ 98,817us-gaap_CargoAndFreightRevenue
Intersegment revenue
Total revenue earned			1,584us-gaap_SalesRevenueServicesNet
Amortization
Total consolidated depreciation and amortization			36,714
Interest expense
Total consolidated interest expense			7,620us-gaap_InterestExpense
Net loss
Net (loss) income	(190,795)us-gaap_ProfitLoss	(22,562)us-gaap_ProfitLoss	(213,358)us-gaap_ProfitLoss
Total assets
Total consolidated assets	1,752,913us-gaap_Assets		1,752,913us-gaap_Assets	1,752,913us-gaap_Assets
Expenditures for vessels
Total consolidated expenditures for vessels			24,473gnk_ExpenditureForVessels
Operating Segments
Voyage revenue from external customers
Total consolidated voyage revenue from external customers			98,817
Intersegment revenue
Total revenue earned			2,309
Amortization
Total consolidated depreciation and amortization			36,716
Interest expense
Total consolidated interest expense			7,620
Net loss
Net (loss) income			(212,953)
Total assets
Total consolidated assets	1,753,338		1,753,338	1,753,338
Expenditures for vessels
Total consolidated expenditures for vessels			24,753
Intersegment Elimination
Intersegment revenue
Total revenue earned			(2,309)
Amortization
Total consolidated depreciation and amortization			(2)
Net loss
Net (loss) income			405
Total assets
Total consolidated assets	(425)		(425)	(425)
Expenditures for vessels
Total consolidated expenditures for vessels			(280)
Predecessor
Voyage revenue from external customers
Total consolidated voyage revenue from external customers												118,759	118,759	224,179	223,159
Intersegment revenue
Total revenue earned													1,701	3,285	3,294
Amortization
Total consolidated depreciation and amortization													75,952	140,743	139,063
Interest expense
Total consolidated interest expense													41,061	88,216	87,558
Net loss
Net (loss) income					892,351	(65,557)	(42,238)	(19,155)	(36,976)	(48,940)	(51,950)		784,557	(157,021)	(157,776)
Total assets
Total consolidated assets								2,957,254						2,957,254
Expenditures for vessels
Total consolidated expenditures for vessels													29,995	145,350	1,155
Predecessor \| Operating Segments
Voyage revenue from external customers
Total consolidated voyage revenue from external customers												118,759		224,179	223,159
Intersegment revenue
Total revenue earned													2,156	4,571	2,816
Amortization
Total consolidated depreciation and amortization													76,066	140,908	139,219
Interest expense
Total consolidated interest expense													41,061	88,216	87,558
Net loss
Net (loss) income													784,697	(155,446)	(156,565)
Total assets
Total consolidated assets								2,962,178						2,962,178
Expenditures for vessels
Total consolidated expenditures for vessels													29,995	146,790	1,155
Predecessor \| Intersegment Elimination
Intersegment revenue
Total revenue earned													(2,156)	(4,571)	(2,816)
Amortization
Total consolidated depreciation and amortization													(114)	(165)	(156)
Net loss
Net (loss) income													140	1,575	1,211
Total assets
Total consolidated assets								(4,924)						(4,924)
Expenditures for vessels
Total consolidated expenditures for vessels														(1,440)
GS&T \| Operating Segments
Voyage revenue from external customers
Total consolidated voyage revenue from external customers			77,885
Intersegment revenue
Total revenue earned			2,309
Amortization
Total consolidated depreciation and amortization			28,922
Interest expense
Total consolidated interest expense			4,791
Net loss
Net (loss) income			(177,921)
Total assets
Total consolidated assets	1,270,923		1,270,923	1,270,923
Expenditures for vessels
Total consolidated expenditures for vessels			831
GS&T \| Predecessor \| Operating Segments
Voyage revenue from external customers
Total consolidated voyage revenue from external customers												94,171		188,206	195,855
Intersegment revenue
Total revenue earned													2,156	4,571	2,816
Amortization
Total consolidated depreciation and amortization													65,237	125,344	124,405
Interest expense
Total consolidated interest expense													37,998	83,761	83,306
Net loss
Net (loss) income													878,127	(144,054)	(139,295)
Total assets
Total consolidated assets								2,404,811						2,404,811
Expenditures for vessels
Total consolidated expenditures for vessels													1,043	192	1,155
Baltic Trading
Intersegment revenue
Percentage of purchase fee capitalized as part of vessel assets (as a percent)				100.00%
Baltic Trading \| Operating Segments
Voyage revenue from external customers
Total consolidated voyage revenue from external customers			20,932
Amortization
Total consolidated depreciation and amortization			7,794
Interest expense
Total consolidated interest expense			2,829
Net loss
Net (loss) income			(35,032)
Total assets
Total consolidated assets	482,415		482,415	482,415
Expenditures for vessels
Total consolidated expenditures for vessels			23,922
Baltic Trading \| Predecessor \| Operating Segments
Voyage revenue from external customers
Total consolidated voyage revenue from external customers												24,588		35,973	27,304
Amortization
Total consolidated depreciation and amortization													10,829	15,564	14,814
Interest expense
Total consolidated interest expense													3,063	4,455	4,252
Net loss
Net (loss) income													(93,430)	(11,392)	(17,270)
Total assets
Total consolidated assets								557,367						557,367
Expenditures for vessels
Total consolidated expenditures for vessels													$ 28,952	$ 146,598