XML 75 R61.htm IDEA: XBRL DOCUMENT
v3.8.0.1

EMPLOYEE BENEFIT PLANS - Plan assets using fair value hierarchy (Details) - Retirement Income Plan - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
--- | --- | --- | ---
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total Assets in the Fair Value Hierarchy |  | $ 6,722 | $ 6,032 | $ 5,813
Total |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total Assets in the Fair Value Hierarchy |  | 6,031 | 4,520 |
Investments measured at Net Asset Value |  | 691 | 1,512 |
Investments at Fair Value |  | 6,722 | 6,032 |
Level 1 |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total Assets in the Fair Value Hierarchy |  | 1,239 | 975 |
Level 2 |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total Assets in the Fair Value Hierarchy |  | 4,792 | 3,545 |
Cash and Cash Equivalents | Total |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total Assets in the Fair Value Hierarchy | [1] | 192 | 200 |
Cash and Cash Equivalents | Level 1 |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total Assets in the Fair Value Hierarchy | [1] | 192 | 200 |
Cash and Cash Equivalents | Level 2 |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total Assets in the Fair Value Hierarchy | [1] | 0 | 0 |
Fixed Income Securities | Total |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total Assets in the Fair Value Hierarchy | [2] | 1,601 | 1,529 |
Fixed Income Securities | Level 1 |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total Assets in the Fair Value Hierarchy | [2] | 0 | 0 |
Fixed Income Securities | Level 2 |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total Assets in the Fair Value Hierarchy | [2] | 1,601 | 1,529 |
Domestic Equity Securities | Total |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total Assets in the Fair Value Hierarchy | [3] | 2,844 | 1,539 |
Domestic Equity Securities | Level 1 |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total Assets in the Fair Value Hierarchy | [3] | 1,047 | 775 |
Domestic Equity Securities | Level 2 |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total Assets in the Fair Value Hierarchy | [3] | 1,797 | 764 |
International Equity Securities | Total |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total Assets in the Fair Value Hierarchy | [4] | 1,394 | 1,252 |
International Equity Securities | Level 1 |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total Assets in the Fair Value Hierarchy | [4] | 0 | 0 |
International Equity Securities | Level 2 |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Total Assets in the Fair Value Hierarchy | [4] | $ 1,394 | $ 1,252 |
[1] | Cash and cash equivalents, which are used to pay benefits and plan administrative expenses, are held in Rule 2a-7 money market funds.
[2] | Fixed income securities are primarily valued using a market approach with inputs that include broker quotes, benchmark yields, base spreads and reported trades.
[3] | Domestic equity securities are valued using a market approach based on the quoted market prices of identical instruments in their respective markets.
[4] | International equity securities are valued using a market approach based on the quoted market prices of identical instruments in their respective markets.

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

X
- Definition Fair value of assets that have been segregated and restricted to provide pension or postretirement benefits. Assets include, but are not limited to, stocks, bonds, other investments, earnings from investments, and contributions by the employer and employees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method. + 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(12)) -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 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(5)) -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 320 -SubTopic 10 -Section 35 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=82895926&loc=d3e24584-111560 Reference 4: 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(6)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 5: 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(2)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=75030427&loc=d3e22054-111558 Reference 7: 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)(1)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
Name: | us-gaap_InvestmentsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Net asset value of investment in certain entities that calculate net asset value per share. Includes, but is not limited to, by unit, membership interest, or other ownership interest. Investment includes, but is not limited to, investment in certain hedge funds, venture capital funds, private equity funds, real estate partnerships or funds. Excludes fair value disclosure. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 6A -URI http://asc.fasb.org/extlink&oid=66048111&loc=SL6742756-110258 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 35 -Paragraph 59 -URI http://asc.fasb.org/extlink&oid=65894324&loc=SL6740821-110257 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 35 -Paragraph 54B -URI http://asc.fasb.org/extlink&oid=65894324&loc=SL7495116-110257 + Details
Name: | us-gaap_InvestmentsNetAssetValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_RetirementPlanTypeAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByMeasurementBasisAxis=us-gaap_EstimateOfFairValueFairValueDisclosureMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_CashAndCashEquivalentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_DebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=mpx_DomesticEquitySecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=mpx_InternationalEquitySecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |