Segment Reporting - Schedule of Company's Revenue and Income From Operations by Segment (Details) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2018 |
Sep. 30, 2017 |
Sep. 30, 2018 |
Sep. 30, 2017 |
|
| Segment Reporting Information [Line Items] | ||||
| Revenues | $ 175,915 | $ 91,238 | $ 516,039 | $ 330,512 |
| Voyage expenses | (83,048) | (18,303) | (249,974) | (61,488) |
| Vessel operating expenses | (52,161) | (40,958) | (157,808) | (131,949) |
| Time-charter hire expense | (4,317) | (5,835) | (14,697) | (27,459) |
| Depreciation and amortization | (29,595) | (24,328) | (88,598) | (73,652) |
| General and administrative expenses | (8,747) | (7,622) | (27,939) | (24,875) |
| (Loss) gain on sale of vessels | 0 | (7,926) | 170 | (12,495) |
| Restructuring charges | (213) | 0 | (1,195) | 0 |
| Loss from operations | (2,166) | (13,734) | (24,002) | (1,406) |
| Equity loss | (359) | (274) | 265 | (27,174) |
| Operating Segments | Conventional Tanker Segment | ||||
| Segment Reporting Information [Line Items] | ||||
| Revenues | 166,423 | 81,758 | 490,083 | 299,154 |
| Voyage expenses | (85,575) | (20,725) | (259,079) | (69,517) |
| Vessel operating expenses | (43,432) | (32,227) | (131,886) | (100,586) |
| Time-charter hire expense | (2,935) | (4,629) | (10,326) | (23,698) |
| Depreciation and amortization | (28,532) | (23,071) | (85,171) | (69,857) |
| General and administrative expenses | (7,985) | (6,823) | (25,385) | (22,258) |
| (Loss) gain on sale of vessels | (7,968) | 0 | (12,545) | |
| Restructuring charges | 0 | (152) | ||
| Loss from operations | (2,036) | (13,685) | (21,916) | 693 |
| Equity loss | (359) | (274) | 265 | (27,174) |
| Operating Segments | Ship-to-Ship Transfer Segment | ||||
| Segment Reporting Information [Line Items] | ||||
| Revenues | 12,019 | 11,902 | 35,061 | 39,387 |
| Voyage expenses | 0 | 0 | 0 | 0 |
| Vessel operating expenses | (8,729) | (8,731) | (25,922) | (31,363) |
| Time-charter hire expense | (1,382) | (1,206) | (4,371) | (3,761) |
| Depreciation and amortization | (1,063) | (1,257) | (3,427) | (3,795) |
| General and administrative expenses | (762) | (799) | (2,554) | (2,617) |
| (Loss) gain on sale of vessels | 42 | 170 | 50 | |
| Restructuring charges | (213) | (1,043) | ||
| Loss from operations | (130) | (49) | (2,086) | (2,099) |
| Equity loss | 0 | 0 | 0 | 0 |
| Inter-segment Adjustment | ||||
| Segment Reporting Information [Line Items] | ||||
| Revenues | (2,527) | (2,422) | (9,105) | (8,029) |
| Voyage expenses | 2,527 | 2,422 | 9,105 | 8,029 |
| Vessel operating expenses | 0 | 0 | 0 | 0 |
| Time-charter hire expense | 0 | 0 | 0 | 0 |
| Depreciation and amortization | 0 | 0 | 0 | 0 |
| General and administrative expenses | 0 | 0 | 0 | 0 |
| (Loss) gain on sale of vessels | 0 | 0 | 0 | |
| Restructuring charges | 0 | 0 | ||
| Loss from operations | 0 | 0 | 0 | 0 |
| Equity loss | $ 0 | $ 0 | $ 0 | $ 0 |