XML 124 R70.htm IDEA: XBRL DOCUMENT
v3.5.0.2

Transactions with Related Parties, Convertible Promissory Notes - 6K (Details) $ / shares in Units, $ in Thousands |  | 3 Months Ended | 9 Months Ended | 12 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | ---
Mar. 12, 2015 USD ($) Installment $ / shares | Dec. 31, 2015 USD ($) | Sep. 30, 2016 USD ($) Installment Amendment $ / shares | Sep. 30, 2015 USD ($) | Dec. 31, 2015 USD ($) | Dec. 31, 2014 USD ($) | Dec. 31, 2013 USD ($) | Jun. 16, 2016 USD ($) | Dec. 14, 2015 USD ($) | Dec. 01, 2015 USD ($) | Sep. 07, 2015 USD ($) $ / shares
Applicable Limit [Abstract] |  |  |  |  |  |  |  |  |  |  |
Beginning balance |  |  | $ 178,447 | $ 0 | $ 0 |  |  |  |  |  |
Additions |  |  | 9,400 | 6,800 | 15,765 | $ 0 | $ 0 |  |  |  |
Ending balance |  | $ 178,447 | 178,064 |  | 178,447 | 0 |  |  |  |  |
Accumulated Deficit [Abstract] |  |  |  |  |  |  |  |  |  |  |
Amortization of debt discount |  |  | 688 | 227 | 334 | 0 | 0 |  |  |  |
Partial extinguishment of debt |  |  | 0 | 200 | 200 | 0 | 0 |  |  |  |
Debt [Abstract] |  |  |  |  |  |  |  |  |  |  |
Partial extinguishment of debt |  |  | 0 | (200) | (200) | 0 | 0 |  |  |  |
Additional Paid-in Capital [Abstract] |  |  |  |  |  |  |  |  |  |  |
Intrinsic value of BCF |  |  |  | 6,800 | 15,765 |  |  |  |  |  |
Intrinsic value of BCF |  |  | 9,400 |  |  |  |  |  |  |  |
Consideration allocated to repurchase of BCF |  |  | 0 | 200 | 200 | 0 | $ 0 |  |  |  |
Unsecured Convertible Promissory Note [Member] |  |  |  |  |  |  |  |  |  |  |
Convertible Promissory Notes [Abstract] |  |  |  |  |  |  |  |  |  |  |
Convertible promissory notes |  | 4,000 |  |  | 4,000 |  |  |  |  |  |
Applicable Limit [Abstract] |  |  |  |  |  |  |  |  |  |  |
Beginning balance |  |  | 4,000 | 0 | 0 |  |  |  |  |  |
Additions |  |  |  | 4,000 |  |  |  |  |  |  |
Ending balance |  | 4,000 | 4,000 | 4,000 | 4,000 | 0 |  |  |  |  |
Debt Discount [Abstract] |  |  |  |  |  |  |  |  |  |  |
Beginning balance |  |  | (4,000) | 0 | 0 |  |  |  |  |  |
Additions |  |  |  | (4,000) |  |  |  |  |  |  |
Ending balance |  | (4,000) | (4,000) | (4,000) | (4,000) | 0 |  |  |  |  |
Accumulated Deficit [Abstract] |  |  |  |  |  |  |  |  |  |  |
Beginning balance |  |  | 103 | 0 | 0 |  |  |  |  |  |
Amortization of debt discount |  | 78 | 222 | 225 | 303 |  |  |  |  |  |
Partial extinguishment of debt |  |  |  | (200) | (200) |  |  |  |  |  |
Ending balance |  | 103 | 325 | 25 | 103 | 0 |  |  |  |  |
Debt [Abstract] |  |  |  |  |  |  |  |  |  |  |
Beginning balance |  |  | 103 | 0 | 0 |  |  |  |  |  |
Amortization (Note 12) |  | 78 | 222 | 225 |  |  |  |  |  |  |
Partial extinguishment of debt |  |  |  | (200) | (200) |  |  |  |  |  |
Ending balance |  | 103 | 325 | 25 | 103 | 0 |  |  |  |  |
Additional Paid-in Capital [Abstract] |  |  |  |  |  |  |  |  |  |  |
Beginning balance |  |  | 3,800 | 0 | 0 |  |  |  |  |  |
Intrinsic value of BCF |  |  |  |  | 4,000 |  |  |  |  |  |
Consideration allocated to repurchase of BCF |  |  |  | (200) | (200) |  |  |  |  |  |
Ending balance |  | 3,800 | 3,800 |  | 3,800 | 0 |  |  |  |  |
Unsecured Revolving Convertible Promissory Note [Member] |  |  |  |  |  |  |  |  |  |  |
Convertible Promissory Notes [Abstract] |  |  |  |  |  |  |  |  |  |  |
Convertible promissory notes |  | 11,765 |  |  | 11,765 |  |  |  |  |  |
Applicable Limit [Abstract] |  |  |  |  |  |  |  |  |  |  |
Beginning balance |  |  | 11,765 | 0 | 0 |  |  |  |  |  |
Additions |  | 8,965 | 9,400 | 2,800 |  |  |  |  |  |  |
Ending balance |  | 11,765 | 21,165 | 2,800 | 11,765 | 0 |  |  |  |  |
Debt Discount [Abstract] |  |  |  |  |  |  |  |  |  |  |
Beginning balance |  |  | (11,765) | 0 | 0 |  |  |  |  |  |
Additions |  | (8,965) | (9,400) | (2,800) |  |  |  |  |  |  |
Ending balance |  | (11,765) | (21,165) | (2,800) | (11,765) | 0 |  |  |  |  |
Accumulated Deficit [Abstract] |  |  |  |  |  |  |  |  |  |  |
Beginning balance |  |  | 31 | 0 | 0 |  |  |  |  |  |
Amortization of debt discount |  | 29 | 466 | 2 | 31 |  |  |  |  |  |
Ending balance |  | 31 | 497 | 2 | 31 | 0 |  |  |  |  |
Debt [Abstract] |  |  |  |  |  |  |  |  |  |  |
Beginning balance |  |  | 31 | 0 | 0 |  |  |  |  |  |
Amortization (Note 12) |  | 29 | 466 | 2 |  |  |  |  |  |  |
Ending balance |  | 31 | 497 | 2 | 31 | 0 |  |  |  |  |
Additional Paid-in Capital [Abstract] |  |  |  |  |  |  |  |  |  |  |
Beginning balance |  |  | 11,765 | $ 0 | 0 |  |  |  |  |  |
Intrinsic value of BCF |  |  |  |  | 11,765 |  |  |  |  |  |
Intrinsic value of BCF |  |  | 9,400 |  |  |  |  |  |  |  |
Ending balance |  | $ 11,765 | $ 21,165 |  | $ 11,765 | $ 0 |  |  |  |  |
Jelco [Member] | Unsecured Convertible Promissory Note [Member] |  |  |  |  |  |  |  |  |  |  |
Convertible Promissory Notes [Abstract] |  |  |  |  |  |  |  |  |  |  |
Convertible promissory notes | $ 4,000 |  |  |  |  |  |  |  |  |  |
Number of consecutive payment installments | Installment | 10 |  | 10 |  |  |  |  |  |  |  |
Frequency of periodic payment |  |  | Semi-annual |  |  |  |  |  |  |  |
Installment payment | $ 200 |  | $ 200 |  |  |  |  |  |  |  |
Balloon payment | $ 2,000 |  | $ 2,000 |  |  |  |  |  |  |  |
Maturity date | Mar. 19, 2020 |  | Mar. 19, 2020 |  |  |  |  |  |  |  |
Conversion price of convertible notes into common stock (in dollars per share) | $ / shares | $ 0.90 |  | $ 0.90 |  |  |  |  |  |  |  |
Jelco [Member] | Unsecured Convertible Promissory Note [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |
Convertible Promissory Notes [Abstract] |  |  |  |  |  |  |  |  |  |  |
Number of consecutive payment installments that can be deferred | Installment | 3 |  | 3 |  |  |  |  |  |  |  |
Jelco [Member] | Unsecured Revolving Convertible Promissory Note [Member] |  |  |  |  |  |  |  |  |  |  |
Convertible Promissory Notes [Abstract] |  |  |  |  |  |  |  |  |  |  |
Conversion price of convertible notes into common stock (in dollars per share) | $ / shares |  |  |  |  |  |  |  |  |  |  | $ 0.90
Additional Paid-in Capital [Abstract] |  |  |  |  |  |  |  |  |  |  |
Maximum principal amount available to be drawn |  |  |  |  |  |  |  | $ 21,165 | $ 11,765 | $ 9,765 | $ 6,765
Decrease in Applicable Limit |  |  |  |  |  |  |  | $ (3,100) | $ (2,000) |  | $ (1,000)
Number of amendments | Amendment |  |  | 7 |  |  |  |  |  |  |  |
Jelco [Member] | Unsecured Revolving Convertible Promissory Note [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |
Additional Paid-in Capital [Abstract] |  |  |  |  |  |  |  |  |  |  |
Tenor of note |  |  | 5 years |  | 5 years |  |  |  |  |  |

X
- Definition Amount of accumulated amortization for debt discount and premium associated with the related debt instruments. + References No definition available. + Details
Name: | ship_AccumulatedAmortizationDebtDiscountPremium
Namespace Prefix: | ship_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- References No definition available. + Details
Name: | ship_AccumulatedDeficitAbstract
Namespace Prefix: | ship_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | ship_ApplicableLimitAbstract
Namespace Prefix: | ship_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of increase (decrease) in the carrying amount of the convertible notes for the period. + References No definition available. + Details
Name: | ship_ConvertibleNotesPayableIncreaseDecreaseNet
Namespace Prefix: | ship_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- References No definition available. + Details
Name: | ship_DebtDiscountAbstract
Namespace Prefix: | ship_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The maximum principal amount available for drawing at any relevant time under the agreement. + References No definition available. + Details
Name: | ship_DebtInstrumentApplicableLimit
Namespace Prefix: | ship_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Increase (decrease) in the Applicable Limit under the agreement. The Applicable Limit is the maximum principal amount available for drawing at any relevant time under the agreement. + References No definition available. + Details
Name: | ship_DebtInstrumentIncreaseDecreaseInApplicableLimit
Namespace Prefix: | ship_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The number of times the debt has been amended. + References No definition available. + Details
Name: | ship_DebtInstrumentNumberOfAmendments
Namespace Prefix: | ship_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition The number of consecutive, periodic payment installments in which the debt is to be repaid. + References No definition available. + Details
Name: | ship_DebtInstrumentNumberOfConsecutivePaymentInstallments
Namespace Prefix: | ship_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of consecutive payment installments that can be deferred prior to the balloon installment. + References No definition available. + Details
Name: | ship_DebtInstrumentNumberOfConsecutivePaymentInstallmentsThatCanBeDeferred
Namespace Prefix: | ship_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Additions to unamortized debt discount during the period. + References No definition available. + Details
Name: | ship_DebtInstrumentUnamortizedDiscountAdditions
Namespace Prefix: | ship_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of debt discount before accumulated amortization. + References No definition available. + Details
Name: | ship_DebtInstrumentUnamortizedDiscountGross
Namespace Prefix: | ship_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Adjustment to additional paid in capital resulting from the recognition of convertible debt instruments as two separate components - a debt component and an equity component. This bifurcation may result in a basis difference associated with the liability component that represents a temporary difference for purposes of applying accounting for income taxes. The initial recognition of deferred taxes for the tax effect of that temporary difference is as an adjustment to additional paid in capital. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 25 -Paragraph 22 -URI http://asc.fasb.org/extlink&oid=51819886&loc=SL6014347-161799 + Details
Name: | us-gaap_AdjustmentsToAdditionalPaidInCapitalEquityComponentOfConvertibleDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of subsequent adjustments to additional paid in capital for convertible financial instruments where a component of equity and a component of debt are recognized. + References No definition available. + Details
Name: | us-gaap_AdjustmentsToAdditionalPaidInCapitalEquityComponentOfConvertibleDebtSubsequentAdjustments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 1A -URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.8) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 + Details
Name: | us-gaap_AmortizationOfDebtDiscountPremium
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_ConvertibleLongtermNotesPayableCurrentAndNoncurrentAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Including the current and noncurrent portions, carrying value as of the balance sheet date of a written promise to pay a note, initially due after one year or beyond the operating cycle if longer, which can be exchanged for a specified amount of one or more securities (typically common stock), at the option of the issuer or the holder. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.6-04(13)) -URI http://asc.fasb.org/extlink&oid=6488278&loc=d3e603758-122996 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)(a)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_ConvertibleNotesPayable
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition 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. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(16)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
Name: | us-gaap_DebtInstrumentCarryingAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The carrying amount of the equity component of convertible debt which may be settled in cash upon conversion. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6928298&loc=SL6031897-161870 + Details
Name: | us-gaap_DebtInstrumentConvertibleCarryingAmountOfTheEquityComponent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The price per share of the conversion feature embedded in the debt instrument. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6928298&loc=SL6031898-161870 + Details
Name: | us-gaap_DebtInstrumentConvertibleConversionPrice1
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Face (par) amount of debt instrument at time of issuance. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399 + Details
Name: | us-gaap_DebtInstrumentFaceAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Description of the frequency of periodic payments (monthly, quarterly, annual). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 470 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentFrequencyOfPeriodicPayment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(2)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentMaturityDate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of the required periodic payments applied to principal. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentPeriodicPaymentPrincipal
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of payment greater than the preceding installment payments to be paid at final maturity date of debt. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentPeriodicPaymentTermsBalloonPaymentToBePaid
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- 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. + Details
Name: | us-gaap_DebtInstrumentTerm
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_EquityAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 50 -Section 40 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=49170532&loc=d3e12317-112629 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 50 -Section 40 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=49170532&loc=d3e12355-112629 + Details
Name: | us-gaap_GainsLossesOnExtinguishmentOfDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_LongtermConvertibleDebtCurrentAndNoncurrentAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The cash inflow from the issuance of a long-term debt instrument which can be exchanged for a specified amount of another security, typically the entity's common stock, at the option of the issuer or the holder. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Financing Activities -URI http://asc.fasb.org/extlink&oid=6513228 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3255-108585 + Details
Name: | us-gaap_ProceedsFromConvertibleDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The cash outflow from the repayment of a long-term debt instrument which can be exchanged for a specified amount of another security, typically the entity's common stock, at the option of the issuer or the holder. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Financing Activities -URI http://asc.fasb.org/extlink&oid=6513228 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3291-108585 + Details
Name: | us-gaap_RepaymentsOfConvertibleDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_DebtInstrumentAxis=ship_UnsecuredConvertiblePromissoryNoteMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=ship_UnsecuredRevolvingConvertiblePromissoryNoteMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=ship_JelcoDeltaHoldingCorpMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |