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deferred finance costs, net.

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Total US Dollar floating rate debt

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Carrying amount at the balance sheet date of vessels and other long-lived depreciable physical assets used in the normal conduct of business and not intended for resale, net of accumulated depreciation on vessels and equipments.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Face (par) amount of debt instrument at time of issuance.

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Net increase or decrease in the carrying amount of the debt instrument for the period.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount, before effects of master netting arrangements, of financial assets loaned to entities in exchange for collateral and funds outstanding borrowed in the form of a financial asset repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same financial assets at a date certain for a specified price. Includes liabilities not subject to a master netting arrangement.

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DEBT (Details) - USD ($)	1 Months Ended			6 Months Ended	12 Months Ended
DEBT (Details) - USD ($)	Jul. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Aug. 31, 2016	Jun. 30, 2016	Dec. 31, 2014
Debt Instrument [Line Items]
Total debt					$ 1,592,410,000	$ 992,631,000
Total US Dollar floating rate debt					1,492,056,000	992,620,000
Long-term Line of Credit					42,000	11,000
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement					10,312,000	0
Long-term Debt, Current Maturities					113,076,000	67,365,000
Deferred finance costs, net					12,260,000	10,674,000
Long-term Debt, Excluding Current Maturities					1,467,074,000	914,592,000
Maturities of Long-term Debt [Abstract]
2018					113,076,000
2019					192,793,000
2020					412,344,000
2021					410,637,000
2022					38,242,000
Thereafter					425,318,000
Assets pledged [Abstract]
Vessels, net,					2,342,130,000	1,477,395,000
Vessels by Name [Member]
Assets pledged [Abstract]
Vessels, net,					2,341,069,000	1,476,889,000
Term loan facility, $109.2 Million [Member]
Assets pledged [Abstract]
Debt Instrument, Increase (Decrease), Net				$ 54,600,000
Term loan facility $328.4 million [Member]
Assets pledged [Abstract]
Debt Instrument, Increase (Decrease), Net				165,900,000
Term loan facility $321.6 million [Member]
Debt Instrument [Line Items]
Principal amount				321,600,000
Term loan facility $110.5 million ING [Member]
Debt Instrument [Line Items]
Principal amount				110,500,000	110,500,000
Term loan facility $110.5 million CS [Member]
Debt Instrument [Line Items]
Principal amount				$ 110,500,000
Senior unsecured facility $275.0 million [Member]
Debt Instrument [Line Items]
Principal amount									$ 275,000,000.0
Assets pledged [Abstract]
Debt Instrument, Increase (Decrease), Net					90,000,000
Loans Payable [Member]
Debt Instrument [Line Items]
Total debt					90,000,000	0
Loans Payable [Member] \| Term Loan Facility, $500.1 Million [Member]
Debt Instrument [Line Items]
Principal amount		$ 500,100,000.0					$ 500,100,000.0
Loans Payable [Member] \| Term Loan Facility, $500.1 Million [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Assets pledged [Abstract]
Basis spread on variable interest rate		1.90%
Loans Payable [Member] \| Term Loan Facility, $60.6 Million [Member]
Debt Instrument [Line Items]
Principal amount			$ 60,600,000.0
Loans Payable [Member] \| Term Loan Facility, $60.6 Million [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Assets pledged [Abstract]
Basis spread on variable interest rate			1.80%
Loans Payable [Member] \| Term Loan Facility, $466.5 Million [Member]
Debt Instrument [Line Items]
Principal amount										$ 466,500,000.0
Assets pledged [Abstract]
Debt Instrument, Increase (Decrease), Net						192,400,000	$ 99,000,000
Loans Payable [Member] \| Term loan facility, $109.2 Million [Member]
Debt Instrument [Line Items]
Principal amount	$ 109,200,000.0
Loans Payable [Member] \| Term loan facility, $109.2 Million [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Assets pledged [Abstract]
Basis spread on variable interest rate	1.90%
Loans Payable [Member] \| Term loan facility $328.4 million [Member]
Debt Instrument [Line Items]
Principal amount								$ 328,400,000
Assets pledged [Abstract]
Debt Instrument, Increase (Decrease), Net						109,000,000
Loans Payable [Member] \| Term loan facility $321.6 million [Member]
Debt Instrument [Line Items]
Principal amount					321,600,000
Assets pledged [Abstract]
Debt Instrument, Increase (Decrease), Net					252,700,000
Loans Payable [Member] \| Term loan facility $110.5 million ING [Member]
Assets pledged [Abstract]
Debt Instrument, Increase (Decrease), Net					$ 55,300,000
Loans Payable [Member] \| Term loan facility $110.5 million ING [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Assets pledged [Abstract]
Basis spread on variable interest rate					1.90%
Loans Payable [Member] \| Term loan facility $110.5 million CS [Member]
Assets pledged [Abstract]
Debt Instrument, Increase (Decrease), Net					$ 54,900,000
Loans Payable [Member] \| Senior unsecured facility $275.0 million [Member]
Debt Instrument [Line Items]
Total debt					90,000,000	0
Principal amount					275,000,000.0				$ 275,000,000.0
US Dollar denominated floating rate debt [Member] \| Term Loan Facility, $466.5 Million [Member]
Debt Instrument [Line Items]
Total debt						466,500,000
US Dollar denominated floating rate debt [Member] \| Loans Payable [Member] \| Term Loan Facility, $500.1 Million [Member]
Debt Instrument [Line Items]
Total debt					423,894,000	461,997,000
Principal amount					500,100,000
US Dollar denominated floating rate debt [Member] \| Loans Payable [Member] \| Term Loan Facility, $60.6 Million [Member]
Debt Instrument [Line Items]
Total debt					51,062,000	54,530,000
Principal amount					60,600,000
US Dollar denominated floating rate debt [Member] \| Loans Payable [Member] \| Term Loan Facility, $466.5 Million [Member]
Debt Instrument [Line Items]
Total debt					297,794,000	314,315,000
Principal amount					466,500,000
US Dollar denominated floating rate debt [Member] \| Loans Payable [Member] \| Term loan facility, $109.2 Million [Member]
Debt Instrument [Line Items]
Total debt					102,776,000	53,797,000
Principal amount					109,200,000
US Dollar denominated floating rate debt [Member] \| Loans Payable [Member] \| Term loan facility $328.4 million [Member]
Debt Instrument [Line Items]
Total debt					261,354,000	107,981,000
Principal amount					328,400,000
US Dollar denominated floating rate debt [Member] \| Loans Payable [Member] \| Term loan facility $321.6 million [Member]
Debt Instrument [Line Items]
Total debt					246,531,000	0
Principal amount					321,600,000
US Dollar denominated floating rate debt [Member] \| Loans Payable [Member] \| Term loan facility $110.5 million ING [Member]
Debt Instrument [Line Items]
Total debt					54,483,000	0
Principal amount					110,500,000
US Dollar denominated floating rate debt [Member] \| Loans Payable [Member] \| Term loan facility $110.5 million CS [Member]
Debt Instrument [Line Items]
Total debt					54,162,000	$ 0
Principal amount					$ 110,500,000