Borrowed aggregate principal amount.

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- Definition

Fixed charge coverage ratio.

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No definition available.

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Lease expiration year.

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- Definition

Line of credit facility optional increase capacity.

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No definition available.

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- Definition

Net book value of related assets.

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No definition available.

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- Definition

Net leverage ratio.

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No definition available.

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- Definition

Percentage of principal to be repaid during fifth year of term.

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No definition available.

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- Definition

Percentage of principal to be repaid yearly during first two years of term.

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No definition available.

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- Definition

Percentage of principal to be repaid yearly during third and fourth years of term.

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No definition available.

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- Definition

Term loan facility bear interest fixed rate.

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No definition available.

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- Definition

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

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No definition available.

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The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

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No definition available.

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- Definition

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

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-SubTopic 30
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- Definition

Incremental percentage increase (decrease) in the stated rate on a debt instrument.

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No definition available.

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- Definition

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

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- Definition

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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- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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- Definition

Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph e
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- Definition

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

+ References

No definition available.

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- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

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- Definition

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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- Definition

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, after unamortized discount or premium, scheduled 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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Carrying amount of long-term debt, net of unamortized discount or premium, excluding amounts to be repaid within one year or the normal operating cycle, if longer (current maturities). Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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The carrying value as of the balance sheet date of the noncurrent portion 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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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition

The cash outflow associated with the acquisition of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale; includes cash outflows to pay for construction of self-constructed assets.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Long-Term Debt (Narrative) (Details) - USD ($)	3 Months Ended
Long-Term Debt (Narrative) (Details) - USD ($)	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Nov. 04, 2014	Jun. 04, 2012
Debt Instrument [Line Items]
Net book value of related assets	$ 148,785,000
Net Leverage Ratio	4.50%
Fixed Charge Coverage Ratio	1.25%
Revolving credit facility	$ 35,000,000		$ 20,000,000
Letters of credit outstanding	49,360,000
Letter of credit remaining borrowing capacity	125,640,000
Borrowed aggregate principal amount			2,640,000	$ 47,360,000
Purchases of property and equipment	14,917,000	$ 20,777,000
Long-term Debt, Current Maturities	7,530,000		$ 7,506,000
7.375% Senior Notes Due In 2019 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 275,000,000
Debt Instrument, Interest Rate, Stated Percentage	7.375%
Maturity date	Feb. 01, 2019
If Redeemed In 2015 [Member] \| 7.375% Senior Notes Due In 2019 [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage	103.70%
If Redeemed In 2016 [Member] \| 7.375% Senior Notes Due In 2019 [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage	101.80%
If Redeemed After 2016 [Member] \| 7.375% Senior Notes Due In 2019 [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage	100.00%
Term Loan Facility [Member]
Debt Instrument [Line Items]
Net book value of related assets	$ 49,227,000
Debt instrument, face amount					$ 50,000,000
Debt Instrument, Term	5 years
Term Loan Facility Bear Interest Fixed Rate	4.655%
Debt Instrument, Interest Rate, Increase (Decrease)	2.00%
Percentage of principal to be repaid yearly during first two years of term	10.00%
Percentage of principal to be repaid yearly during third and fourth years of term	20.00%
Percentage of principal to be repaid during fifth year of term	25.00%
Vessels and Ancillary Equipment [Member]
Debt Instrument [Line Items]
Purchases of property and equipment		15,569,000
Operating leases expiration year	2023
Long-term Debt, Current Maturities		2,396,000
Long-term Debt, Excluding Current Maturities		$ 16,488,000
Vessels and Ancillary Equipment [Member] \| 5.75% Senior Notes Due In 2023 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		5.75%
Maximum [Member] \| LIBOR Rate [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.50%
Maximum [Member] \| Base Rate [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.50%
Minimum [Member] \| LIBOR Rate [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.50%
Minimum [Member] \| Base Rate [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.50%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity						$ 210,000,000
Line of credit facility optional increase capacity						15,000,000
Revolving credit facility, interest rate description	The Credit Agreement is collateralized by a substantial portion of the Company’s operating equipment with a net book value at March 31, 2016 of $148,785. Depending on the Company’s consolidated leverage ratio (as defined in the Credit Agreement), borrowings under the revolving credit facility will bear interest at the option of the Company at either a LIBOR rate plus a margin of between 1.50% to 2.50% per annum or a base rate plus a margin of between 0.50% to 1.50% per annum.
Multicurrency [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity						50,000,000
Swingline Loans [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity						$ 10,000,000