SHORT-TERM AND LONG-TERM DEBT (Details) $ / shares in Units, NOK in Millions | 1 Months Ended | 3 Months Ended | 6 Months Ended | 12 Months Ended | | | | | | |
Nov. 30, 2015USD ($)carrierssubsidiaries | Jul. 31, 2015USD ($)carrierssubsidiaries | Jun. 30, 2015containershipvesselsubsidiaries | Dec. 31, 2014subsidiaries | Nov. 30, 2014USD ($)containershipsubsidiaries | Sep. 30, 2014USD ($)subsidiaries | Aug. 31, 2014USD ($)vesselsubsidiaries | Jun. 30, 2014vesselsubsidiaries | Mar. 31, 2014 | Jan. 31, 2013USD ($)$ / sharesRate | Nov. 30, 2012USD ($)vesselsubsidiaries | Oct. 31, 2012 | May 31, 2011USD ($)vesselsubsidiaries | Mar. 31, 2011USD ($)vesselsubsidiaries | Feb. 28, 2011USD ($) | Nov. 30, 2010USD ($)vesselsubsidiaries | Mar. 31, 2010USD ($) | Feb. 28, 2010USD ($) | Mar. 31, 2008USD ($)vesselsubsidiaries | Jun. 30, 2015NOKcontainership | Mar. 31, 2014shares | Jun. 30, 2016NOKvesselscarriersvesselRate | Jun. 30, 2016USD ($) | Jun. 30, 2015USD ($)containership | Dec. 31, 2015NOKvesselscarriersvesselRate | Dec. 31, 2015USD ($) | Dec. 31, 2013USD ($) | Jun. 30, 2016USD ($)vesselscarriersvessel$ / sharesRate | Feb. 29, 2016vessel | Dec. 31, 2015USD ($)vesselscarriersvesselRate | Mar. 19, 2014NOKRate | Oct. 19, 2012NOKRate | Feb. 10, 2011USD ($)$ / sharesRate |
Debt Instrument [Line Items] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt, Long-term and Short-term, Combined Amount | | | | | | | | | | | | | | | | | | | | | | | | | | | | $ 1,643,997,000 | | $ 1,666,476,000 | | | |
Deferred Finance Costs, Noncurrent, Net | | | | | | | | | | | | | | | | | | | | | | | | | | | | (26,795,000) | | (32,271,000) | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | 1,643,997,000 | | | | | |
Less : current portion of long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | (96,881,000) | | (208,031,000) | | | |
Total long-term debt, non-current portion | | | | | | | | | | | | | | | | | | | | | | | | | | | | 1,520,321,000 | | $ 1,426,174,000 | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
2,014 | | | | | | | | | | | | | | | | | | | | | | | | | | | | 48,451,000 | | | | | |
2,015 | | | | | | | | | | | | | | | | | | | | | | | | | | | | 195,302,000 | | | | | |
2,016 | | | | | | | | | | | | | | | | | | | | | | | | | | | | 537,385,000 | | | | | |
2,017 | | | | | | | | | | | | | | | | | | | | | | | | | | | | 272,060,000 | | | | | |
2,018 | | | | | | | | | | | | | | | | | | | | | | | | | | | | 172,060,000 | | | | | |
Thereafter | | | | | | | | | | | | | | | | | | | | | | | | | | | | 418,739,000 | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | $ 1,643,997,000 | | | | | |
Weighted average interest rate (in hundredths) | Rate | | | | | | | | | | | | | | | | | | | | | | 3.998% | | | 4.22% | | | 3.998% | | 4.22% | | | |
Three month dollar LIBOR rate (in hundredths) | Rate | | | | | | | | | | | | | | | | | | | | | | 0.6541% | | | 0.6127% | | | 0.6541% | | 0.6127% | | | |
Three month Norwegian kroner NIBOR rate (in hundredths) | Rate | | | | | | | | | | | | | | | | | | | | | | 1.01% | | | 1.13% | | | 1.01% | | 1.13% | | | |
Equity component of convertible bond issuance, net | | | | | | | | | | | | | | | | | | | | | | | $ 0 | $ 0 | | $ 0 | | | | | | | |
Number of offshore supply vessels | vessels | | | | | | | | | | | | | | | | | | | | | | 5 | | | | | | 5 | | | | | |
Assets accounted for as direct financing leases and leased to related parties | vessels | | | | | | | | | | | | | | | | | | | | | | 15 | | | 16 | | | 15 | | 16 | | | |
US$ 49 million secured term loan and revolving credit facility [Member] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument, Face Amount | | | | | | | | | | | | | | | | | | | $ 49,000,000 | | | | | | | | | $ 0 | | $ 8,000,000 | | | |
Term of Loan | | | | | | | | | | | | | | | | | | | 10 years | | | | | | | | | | | | | | |
Number of wholly-owned subsidiaries of the Company that entered into secured term loan facility agreement | subsidiaries | | | | | | | | | | | | | | | | | | | 2 | | | | | | | | | | | | | | |
Number of new vessels acquired that were partly funded by secured term loan facility | vessel | | | | | | | | | | | | | | | | | | | 2 | | | | | | | | | | | | | | |
Amount available to draw | | | | | | | | | | | | | | | | | | | | | | | | | | | | 20,000,000 | | | | | |
US$ 43 million secured term loan facility (February 2010) [Member] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument, Face Amount | | | | | | | | | | | | | | | | | | $ 42,600,000 | | | | | | | | | | 24,900,000 | | 26,300,000 | | | |
Term of Loan | | | | | | | | | | | | | | | | | | 5 years | | | | | | | | | | | | | | | |
US$ 43 million secured term loan facility (March 2010) [Member] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument, Face Amount | | | | | | | | | | | | | | | | | $ 42,600,000 | | | | | | | | | | | 24,900,000 | | 26,300,000 | | | |
Term of Loan | | | | | | | | | | | | | | | | | 5 years | | | | | | | | | | | | | | | | |
US$ 54 million secured term loan facility [Member] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument, Face Amount | | | | | | | | | | | | | | | | $ 53,700,000 | | | | | | | | | | | | 32,200,000 | | 34,100,000 | | | |
Term of Loan | | | | | | | | | | | | | | | | 8 years | | | | | | | | | | | | | | | | | |
Number of wholly-owned subsidiaries of the Company that entered into secured term loan facility agreement | subsidiaries | | | | | | | | | | | | | | | | 2 | | | | | | | | | | | | | | | | | |
Number of new vessels acquired that were partly funded by secured term loan facility | vessel | | | | | | | | | | | | | | | | 2 | | | | | | | | | | | | | | | | | |
US$ 95 million secured term loan and revolving credit facility [Member] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument, Face Amount | | | | | | | | | | | | | | | $ 95,000,000 | | | | | | | | | | | | | 22,500,000 | | 22,500,000 | | | |
Term of Loan | | | | | | | | | | | | | | | 7 years | | | | | | | | | | | | | | | | | | |
Amount available to draw | | | | | | | | | | | | | | | | | | | | | | | | | | | | 0 | | | | | |
US$ 75 million secured term loan facility [Member] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument, Face Amount | | | | | | | | | | | | | | $ 75,400,000 | | | | | | | | | | | | | | 47,800,000 | | 50,800,000 | | | |
Term of Loan | | | | | | | | | | | | | | 8 years | | | | | | | | | | | | | | | | | | | |
Number of wholly-owned subsidiaries of the Company that entered into secured term loan facility agreement | subsidiaries | | | | | | | | | | | | | | 3 | | | | | | | | | | | | | | | | | | | |
Number of new vessels acquired that were partly funded by secured term loan facility | vessel | | | | | | | | | | | | | | 3 | | | | | | | | | | | | | | | | | | | |
US$ 171 million secured term loan facility [Member] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument, Face Amount | | | | | | | | | | | | | $ 171,000,000 | | | | | | | | | | | | | | | 116,100,000 | | 122,200,000 | | | |
Term of Loan | | | | | | | | | | | | | 10 years | | | | | | | | | | | | | | | | | | | | |
Number of wholly-owned subsidiaries of the Company that entered into secured term loan facility agreement | subsidiaries | | | | | | | | | | | | | 8 | | | | | | | | | | | | | | | | | | | | |
Number of new vessels acquired that were partly funded by secured term loan facility | vessel | | | | | | | | | | | | | 7 | | | | | | | | | | | | | | | | | | | | |
US Dollar 53.2 Million Secured Term Loan Facility [Member] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument, Face Amount | | | | | | | | | | | $ 53,200,000 | | | | | | | | | | | | | | | | | 37,700,000 | | 39,900,000 | | | |
Term of Loan | | | | | | | | | | | 5 years | | | | | | | | | | | | | | | | | | | | | | |
Number of wholly-owned subsidiaries of the Company that entered into secured term loan facility agreement | subsidiaries | | | | | | | | | | | 2 | | | | | | | | | | | | | | | | | | | | | | |
Number of new vessels acquired that were partly funded by secured term loan facility | vessel | | | | | | | | | | | 2 | | | | | | | | | | | | | | | | | | | | | | |
US Dollar 45 million Secured Term Loan Facility [Member] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | 36,000,000 | | 36,000,000 | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | 36,000,000 | | 36,000,000 | | | |
Debt Instrument, Face Amount | | | | | | | | | | | | | | | | | | | | | | | | | | | | 45,000,000 | | | | | |
Term of Loan | | | | | | | | 5 years | | | | | | | | | | | | | | | | | | | | | | | | | |
Number of wholly-owned subsidiaries of the Company that entered into secured term loan facility agreement | subsidiaries | | | | | | | | 7 | | | | | | | | | | | | | | | | | | | | | | | | | |
Number of new vessels acquired that were partly funded by secured term loan facility | vessel | | | | | | | | 7 | | | | | | | | | | | | | | | | | | | | | | | | | |
Book value of assets pledged under ship mortgages | | | | | | | | | | | | | | | | | | | | | | | | | | | | 2,159,000,000 | | 2,087,000,000 | | | |
US dollar 250 million secured revolving credit facility [Member] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | 80,000,000 | | 73,500,000 | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | 80,000,000 | | 73,500,000 | | | |
Debt Instrument, Face Amount | | | | | | | | | | | | | | | | | | | | | | | | | | | | 250,000,000 | | | | | |
Term of Loan | | | 3 years | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Number of wholly-owned subsidiaries of the Company that entered into secured term loan facility agreement | subsidiaries | | | 17 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Number of new vessels acquired that were partly funded by secured term loan facility | vessel | | | 17 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Amount available to draw | | | | | | | | | | | | | | | | | | | | | | | | | | | | $ 135,600,000 | | | | | |
US dollar 350 Million Senior Unsecured Convertible Bonds Due 2018 [Member] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Stated interest rate | Rate | | | | | | | | | | 3.25% | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument Convertible Bond Period | | | | | | | | | | 10 days | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument, Face Amount | | | | | | | | | | $ 350,000,000 | | | | | | | | | | | | | | | | | | | | | | | |
Conversion price (in dollars per share) | $ / shares | | | | | | | | | | $ 21.945 | | | | | | | | | | | | | | | | | | $ 15.3109 | | | | | |
Premium of conversion price to share price | Rate | | | | | | | | | | 33.00% | | | | | | | | | | | | | | | | | | | | | | | |
Common shares loaned to affiliate | shares | | | | | | | | | | | | | | | | | | | | | 6,060,606 | | | | | | | | | | | | |
Related party share loan fee | | | | | | | | | | $ 1,000,000 | | | | | | | | | | | | | | | | | | | | | | | |
Equity component of convertible bond issuance, net | | | | | | | | | | | | | | | | | | | | | | | | | | | $ 20,700,000 | | | | | | |
Amortization of deferred charges | | | | | | | | | | | | | | | | | | | | | | | $ 2,100,000 | | | | | | | | | | |
3.75% Senior Unsecured Convertible Bonds Due 2016 [Member] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | $ 0 | | 117,500,000 | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | 0 | | 117,500,000 | | | |
Stated interest rate | Rate | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 3.75% |
Debt Instrument Convertible Bond Period | | | | | | | | | | | | | | | 10 days | | | | | | | | | | | | | | | | | | |
Debt Instrument, Face Amount | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | $ 125,000,000 |
Conversion price (in dollars per share) | $ / shares | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | $ 27.05 |
Premium of conversion price to share price | Rate | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 35.00% |
NOK 600 million senior unsecured floating rate bonds due 2017 [Member] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | 67,368,000 | | 63,681,000 | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | 67,368,000 | | 63,681,000 | | | |
Debt Instrument, Face Amount | NOK | | | | | | | | | | | | | | | | | | | | | | NOK 565 | | | NOK 565 | | | | | | | NOK 600 | |
Amount of debt repurchased | NOK | | | | | | | | | | | | | | | | | | | | | | | | | 43 | | | | | | | | |
Proceeds from resale of debt previous purchased | NOK | | | | | | | | | | | | | | | | | | | | NOK 8 | | | | | | | | | | | | | |
Notice of redemption (in days) | | | | | | | | | | | | 30 days | | | | | | | | | | | | | | | | | | | | | |
Redemption price of debt (in hundredths) | Rate | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 100.50% | |
NOK 600 Million Senior Unsecured Floating Rate Bonds Due 2017 (USD) [Member] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument, Face Amount | | | | | | | | | | | | | | | | | | | | | | | | | | | | 67,400,000 | | 63,700,000 | | | |
Senior Unsecured Convertible Bonds Due 2018 [Member] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | 350,000,000 | | 350,000,000 | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | 350,000,000 | | 350,000,000 | | | |
NOK 900 million senior unsecured floating rate bonds due 2019 [Member] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | 90,380,000 | | 85,434,000 | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | 90,380,000 | | 85,434,000 | | | |
Debt Instrument, Face Amount | NOK | | | | | | | | | | | | | | | | | | | | | | 758 | | | NOK 758 | | | | | | NOK 900 | | |
Amount of debt repurchased | NOK | | | | | | | | | | | | | | | | | | | | | | NOK 142 | | | | | | | | | | | |
Notice of redemption (in days) | | | | | | | | | 30 days | | | | | | | | | | | | | | | | | | | | | | | | |
Redemption price of debt (in hundredths) | Rate | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 100.50% | | |
NOK 900 million senior unsecured floating rate bonds due 2019 (USD) [Member] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument, Face Amount | | | | | | | | | | | | | | | | | | | | | | | | | | | | 90,400,000 | | 85,400,000 | | | |
USD denominated floating rate debt (libor plus margin) due through 2026 [Member] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | 1,136,249,000 | | 1,049,861,000 | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | 1,136,249,000 | | 1,049,861,000 | | | |
Floating Rate Debt [Member] | US Dollar 45 million Secured Term Loan Facility [Member] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Line of Credit Facility, Remaining Borrowing Capacity | | | | | | | | | | | | | | | | | | | | | | | | | | | | 9,000,000 | | | | | |
Floating Rate Debt [Member] | US dollar 101 million secured term loan facility [Member] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | 71,700,000 | | 87,800,000 | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | 71,700,000 | | 87,800,000 | | | |
Debt Instrument, Face Amount | | | | | | | $ 101,400,000 | | | | | | | | | | | | | | | | | | | | | | | | | | |
Number of wholly-owned subsidiaries of the Company that entered into secured term loan facility agreement | subsidiaries | | | | | | | 6 | | | | | | | | | | | | | | | | | | | | | | | | | | |
Number of offshore supply vessels | vessel | | | | | | | 6 | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument, Term | | | | | | | 5 years | | | | | | | | | | | | | | | | | | | | | | | | | | |
Floating Rate Debt [Member] | US dollar 20 million secured term loan facility [Member] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | 20,000,000 | | 20,000,000 | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | 20,000,000 | | 20,000,000 | | | |
Debt Instrument, Face Amount | | | | | | $ 20,000,000 | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Number of container vessels | containership | | | 2 | | | | | | | | | | | | | | | | | 2 | | | | 2 | | | | | | | | | |
Number of wholly-owned subsidiaries of the Company that entered into secured term loan facility agreement | subsidiaries | | | | | | 2 | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument, Term | | | | | | 5 years | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Floating Rate Debt [Member] | US dollar 128 million secured term loan facility (September 2014) [Member] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | 113,700,000 | | 117,900,000 | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | 113,700,000 | | 117,900,000 | | | |
Debt Instrument, Face Amount | | | | | | $ 127,500,000 | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Number of container vessels | containership | | | 2 | | | | | | | | | | | | | | | | | 2 | | | | 2 | | | | | | | | | |
Number of wholly-owned subsidiaries of the Company that entered into secured term loan facility agreement | subsidiaries | | | | | | 2 | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument, Term | | | | | | 7 years | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Floating Rate Debt [Member] | US dollar 128 million secured term loan facility (November 2014) [Member] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | 116,900,000 | | 121,100,000 | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | 116,900,000 | | 121,100,000 | | | |
Debt Instrument, Face Amount | | | | | $ 127,500,000 | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Number of container vessels | containership | | | | | 2 | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Number of wholly-owned subsidiaries of the Company that entered into secured term loan facility agreement | subsidiaries | | | | 2 | 2 | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument, Term | | | | 8 years | 7 years | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Floating Rate Debt [Member] | US dollar 39 million secured term loan facility [Member] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | 32,800,000 | | 34,000,000 | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | $ 32,800,000 | | 34,000,000 | | | |
Debt Instrument, Face Amount | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | $ 39,000,000 | | | |
Number of drybulk carriers | carriers | | | | | | | | | | | | | | | | | | | | | | | | | 2 | | | | | 2 | | | |
Floating Rate Debt [Member] | US dollar 250 million secured revolving credit facility [Member] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Number Of Vessels Sold | carriers | | | | | | | | | | | | | | | | | | | | | | 3 | | | | | | 3 | | | | | |
Floating Rate Debt [Member] | US dollar 166 million secured term loan facility [Member] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | $ 152,600,000 | | $ 159,500,000 | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | 152,600,000 | | 159,500,000 | | | |
Debt Instrument, Face Amount | | $ 166,400,000 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Number of wholly-owned subsidiaries of the Company that entered into secured term loan facility agreement | subsidiaries | | 8 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Number of vessels against which loan was secured | carriers | | 8 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument, Term | | 7 years | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Floating Rate Debt [Member] | US dollar 210 million secured term loan facility (Maersk) [Member] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | 206,700,000 | | 70,000,000 | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term debt | | | | | | | | | | | | | | | | | | | | | | | | | | | | $ 206,700,000 | | $ 70,000,000 | | | |
Debt Instrument, Face Amount | $ 210,000,000 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Number of wholly-owned subsidiaries of the Company that entered into secured term loan facility agreement | subsidiaries | 3 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Number of vessels against which loan was secured | carriers | 3 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument, Term | 5 years | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Deep Sea [Member] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term Debt, by Maturity [Abstract] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Assets accounted for as direct financing leases and leased to related parties | vessel | | | | | | | | | | | | | | | | | | | | | | 1 | | | 1 | | | 1 | 1 | 1 | | | |