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The minimum liquidity required by covenants of certain debt currently held by the company. Liquidity is defined as cash, cash equivalents and undrawn committed revolving credit lines with at least six months to maturity.

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The minimum free liquidity and undrawn revolving credit line required by covenants of certain debt currently held by the Company, as a percentage of total debt.

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No definition available.

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Debt Covenant Minimum Hull Coverage Ratio

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Long term Debt, Revolving Credit Facility, Decrease in Amount Available Year Five

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Long-term Debt, Revolving Credit Facility, Decrease in Amount Available Year Four

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Long-term Debt, Revolving Credit Facility, Decrease in Amount Available Year Three

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Long-term Debt, Revolving Credit Facility, Decrease in Amount Available Year Two

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No definition available.

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Number of debt instruments.

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

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Contractual interest rate for funds borrowed, under the debt agreement.

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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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No definition available.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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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 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 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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Period between issuance and maturity of long-term debt, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Weighted average interest rate of long-term debt outstanding calculated at point in time.

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No definition available.

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The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

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Long-Term Debt - Additional Information - Revolvers and Term Loans (Details)	1 Months Ended		3 Months Ended	9 Months Ended	12 Months Ended
	Aug. 31, 2020 USD ($) credit_facility	Jan. 31, 2020 USD ($) credit_facility	Mar. 31, 2020 credit_facility	Sep. 30, 2020 USD ($) credit_facility vessel	Dec. 31, 2019 USD ($) credit_facility
Debt Instrument [Line Items]
Total principal				$ 222,375,000	$ 562,861,000
Repayments of Debt	$ 85,100,000	$ 455,300,000
Weighted-average effective interest rate				2.60%	3.70%
Aggregate annual long-term principal repayments, remainder of 2020				$ 2,800,000
Aggregate annual long-term principal repayments, 2021				11,200,000
Aggregate annual long-term principal repayments, 2022				11,200,000
Aggregate annual long-term principal repayments, 2023				42,200,000
Aggregate annual long-term principal repayments, 2024				$ 155,000,000.0
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Number Of Debt Instruments \| credit_facility		2		1	2
Line of Credit Facility, Maximum Borrowing Capacity				$ 485,600,000	$ 371,500,000
Line of Credit Facility, Remaining Borrowing Capacity				330,600,000	30,400,000
Long-term Debt, Revolving Credit Facility, Decrease in Amount Available Remaining Fiscal Year				47,200,000
Long-term Debt, Revolving Credit Facility, Decrease in Amount Available Year Two				91,400,000
Long-term Debt, Revolving Credit Facility, Decrease in Amount Available Year Three				80,400,000
Long-term Debt, Revolving Credit Facility, Decrease in Amount Available Year Four				65,300,000
Long term Debt, Revolving Credit Facility Decrease in Amount Available Year Five				201,300,000
Total principal				$ 155,000,000	341,132,000
Term Loans
Debt Instrument [Line Items]
Number Of Debt Instruments \| credit_facility	1	2	3	1
Total principal				$ 67,375,000	$ 221,729,000
Debt instrument, interest rate, stated percentage					5.40%
Term Loan Due 2023 [Member]
Debt Instrument [Line Items]
Debt Instrument, Collateral, Number of Vessels \| vessel				4
Debt Covenant Minimum Hull Coverage Ratio				125.00%
Actual Hull Coverage Ratio				182.00%
Minimum liquidity covenant requirement				$ 35,000,000.0
Minimum liquidity as a percentage of consolidated debt covenant requirement				5.00%
Term Loan Due 2023 [Member] \| Term Loans
Debt Instrument [Line Items]
Total principal				$ 67,400,000
2020DebtFacilityMaturinginDecember2024 [Member]
Debt Instrument [Line Items]
Debt Instrument, Collateral, Number of Vessels \| vessel				31
Actual Hull Coverage Ratio				483.00%
Minimum liquidity covenant requirement				$ 35,000,000.0
Minimum liquidity as a percentage of consolidated debt covenant requirement				5.00%
2020DebtFacilityMaturinginDecember2024 [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Total principal				$ 155,000,000.0
Minimum [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate				2.25%
Minimum [Member] \| Term Loan Due 2023 [Member] \| Term Loans
Debt Instrument [Line Items]
Long-term Debt, Term				6 months
Minimum [Member] \| 2020DebtFacilityMaturinginDecember2024 [Member] \| Term Loans
Debt Instrument [Line Items]
Long-term Debt, Term				6 months
Maximum
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate				2.40%
London Interbank Offered Rate (LIBOR) [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate				2.40%
London Interbank Offered Rate (LIBOR) [Member] \| Term Loans
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate				2.25%
London Interbank Offered Rate (LIBOR) [Member] \| Minimum [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate					2.00%
London Interbank Offered Rate (LIBOR) [Member] \| Minimum [Member] \| Term Loans
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate					0.30%
London Interbank Offered Rate (LIBOR) [Member] \| Maximum \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate					2.75%
London Interbank Offered Rate (LIBOR) [Member] \| Maximum \| Term Loans
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate					2.00%