Award Type [Axis] Above Market Leases [Member] Accounting Policies [Abstract] Accounts receivable, trade Accounts payable, trade and other Accounts payable, trade and other Accrued bonus Accrued liabilities Accrued Liabilities, Current Accumulated depreciation Accumulated Depreciation Depletion And Amortization Property Plant And Equipment Accumulated depreciation, beginning balance Accumulated depreciation, ending balance Other comprehensive loss Accumulated Depreciation Depletion And Amortization Sale Of Property Plant And Equipment Accumulated depreciation, vessels' disposals Additional paid-in capital Additional Paid In Capital Additional Paid-in Capital [Member] Adjustments to reconcile net income to net cash provided by / (used in) operating activities: Adjustments to reconcile net income to net cash provided by operating activities: Compensation cost on restricted stock Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Affiliated Entity [Member] Provision for doubtful accounts Amortization of deferred financing costs Amortization of deferred financing costs Amortization of prepaid charter revenue Prepaid charter revenue amortization Impairment losses Impairment charges Total assets Total Assets CURRENT ASSETS: ASSETS Total current assets Total current assets Cash and Cash Equivalents Net increase in cash and cash equivalents Net increase / (decrease) in cash and cash equivalents Cash and cash equivalents Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period Cash and cash equivalents Restricted Cash Change in accounting estimate, financial effect Rights exercised Commitments and Contingencies [Abstract] Commitments and contingencies Commitments and Contingencies Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Common Stock Par Or Stated Value Per Share Common Stock Common Stock [Member] Common stock, $0.01 par value; 500,000,000 shares authorized; 73,890,581 and 73,158,991 issued and outstanding as at June 30, 2015 and December 31, 2014, respectively Common Stock, Value, Issued Common stock shares issued Common Stock Shares Issued Common stock shares authorized Common Stock Shares Authorized Common Stock Dividends Per Share Cash Paid Dividends declared and paid, per share Common stock shares outstanding Common Stock Shares Outstanding Comprehensive Income (Loss), Net of Tax, Attributable to Parent Comprehensive income Other Comprehensive Income / Loss Computer Equipment [Member] Concentration Risk [Line Items] Concentration of Credit Risk Concentration Risk [Table] Concentration Risk, Percentage Variable Interest Entities Principles of Consolidation Commissions Repairs and maintenance Crew wages and related costs Tonnage taxes EXPENSES: Credit Facility [Axis] Credit Facility [Domain] Default Longterm Debt Description Of Violation Or Event Of Default Covenant breach, description Debt instrument description of variable rate basis Debt Instrument Line Items Debt Instrument [Table] Debt instrument issuance date Debt instrument face amount Loan margin percentage Long Term Bank Debt [Abstract] Bank debt, gross Amount drawn down under the loan agreement Bank debt Long-term bank debt Debt Instrument Covenant Description Debt Instrument Priority Unamortized deferred financing costs Related deferred financing costs Debt Instrument Frequency Of Periodic Payment Financing Costs Debt Instrument Periodic Payment Principal Debt instrument, maturity date, description Commitment fees and other Debt instrument maturity date Debt Instruments [Abstract] Deferred Revenue Disclosure [Abstract] Deferred charges, net Deferred Revenue, by Arrangement, Disclosure [Table Text Block] Deferred Revenue Arrangement Type [Domain] Deferred Revenue Arrangement, by Type [Table] Deferred Revenue, current [Abstract] Deferred Revenue, current Deferred Revenue Deferred Revenue Deferred revenue, current Deferred revenue, current Deferred Revenue Arrangement [Line Items] Deferred revenue, non-current Deferred Revenue, non-current Deferred Revenue, non-current Deferred Revenue Arrangement Type [Axis] Actuarial loss Actuarial loss Depreciation and amortization of deferred charges Depreciation for the period Depreciation for the period Vessel Depreciation New Accounting Pronouncements Not Yet Adopted Voyage Expenses [Abstract] Spares and consumable stores Compensation Related Costs, Share-based Payments [Abstract] Dividend Payable Date To Be Paid Day Month And Year Dividend payment date Dividend Declared [Member] Dividends Payable Amount Per Share Dividend per share Dividends [Axis] Dividends, Common Stock, Cash Dividends declared and paid during the period Dividends declared and paid Dividends Payable Date Of Record Day Month And Year Record date of shareholders Dividends [Domain] Due From Related Parties Current Due from related parties Related party financing, non-current Amount drawn under the loan agreement Due to related parties, current Due to Related Parties, Current Earnings Per Share, Basic and Diluted [Abstract] Earnings per common share, basic and diluted Earnings Per Share, Basic and Diluted Earnings Per Share Earnings / (loss) per common share, basic Earnings Per Share Basic Earnings / loss per Common Share Earnings / (loss) per common share, diluted Earnings Per Share Diluted Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items] Earnings Per Share [Abstract] Effects of exchange rates on cash Unrecognized cost for restricted stock awards Period for recognition for unrecognized compensation cost Equity Component [Domain] Equity Method Investments and Joint Ventures [Abstract] Equity Method Investments Equity Method Investments Disclosure [Text Block] Extinguishment Of Debt Amount Fair Value Assets Measured On Recurring And Nonrecurring Basis [Table Text Block] Financial Instruments [Abstract] Fair Value Measurements Financial Instruments Time charter aquired, gross Time charter aquired, gross, beginning balance Time charter aquired, gross, ending balance Finite Lived Intangible Assets Period Increase Decrease Time charter aquired, additions Finite-Lived Intangible Assets [Line Items] Time charter aquired, accumulated amortization Prepaid charter revenue, accumulated amortization Time charter aquired, accumulated amortization, beginning balance Time charter aquired, accumulated amortization, ending balance Time charter aquired, net Prepaid Charter Revenue, Net Prepaid charter revenue from time-charter attached Time charter acquired, net, beginning balance Time charter acquired, net, ending balance Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets by Major Class [Axis] Future Amortization Expense, Year One Prepaid Charter Revenue [Abstract] Future Amortization Expense, Year Two Future Amortization Expense, Year Three Foreign Currency Translation Foreign exchange gains