Note 6 - Long-term Debt (Details Textual)	3 Months Ended
Mar. 31, 2016 USD ($) a	Dec. 31, 2015 USD ($)
Wells Fargo Revolving Loans [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate	3.65%
Wells Fargo Revolving Loans [Member] \| Minimum [Member]
Debt Instrument, Covenant Required Liquidity	$ 3,000,000
Wells Fargo Revolving Loans [Member] \| Maximum [Member]
Debt Instrument Covenant Required Liabilities	175,000,000
Wells Fargo Revolving Loans [Member]
Line of Credit Facility, Commitment Fee Amount	0
Line of Credit Facility, Maximum Borrowing Capacity	25,900,000
Long-term Debt	25,868,000	$ 25,868,000
Debt Instrument, Interest Rate, Stated Percentage		4.00%
First Hawaiian Bank Revolving Line of Credit [Member] \| Minimum [Member]
Debt Instrument, Covenant Required Liquidity	3,000,000
First Hawaiian Bank Revolving Line of Credit [Member] \| Maximum [Member]
Debt Instrument Covenant Required Liabilities	175,000,000
First Hawaiian Bank Revolving Line of Credit [Member]
Line of Credit Facility, Commitment Fee Amount	0
Line of Credit Facility, Maximum Borrowing Capacity	$ 3,500,000
American Ag Credit Term Loan [Member] \| London Interbank Offered Rate (LIBOR) [Member] \| Interest Paid Monthly [Member]
Debt Instrument, Basis Spread on Variable Rate	5.25%
American Ag Credit Term Loan [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate	6.75%
American Ag Credit Term Loan [Member] \| Minimum [Member]
Debt Instrument, Covenant Required Liquidity	$ 3,000,000
American Ag Credit Term Loan [Member] \| Maximum [Member]
Debt Instrument Covenant Required Liabilities	$ 175,000,000
Debt Instrument, Mandatory Principal Repayments as Percentage Net Proceeds of Sale of Non Collateralized Real Property	75.00%
American Ag Credit Term Loan [Member] \| Maximum Balance for a 1.25% Decrease [Member]
Debt Instrument, Interest Rate, Increase (Decrease)	(1.25%)
Debt Instrument, Maximum Amount of Principal Balance Triggering Reduction in Interest Rate	$ 10,000,000
American Ag Credit Term Loan [Member] \| Maximum Balance for an Additional 1.25% Decrease [Member]
Debt Instrument, Interest Rate, Increase (Decrease)	(1.25%)
Debt Instrument, Maximum Amount of Principal Balance Triggering Reduction in Interest Rate	$ 5,000,000
American Ag Credit Term Loan [Member] \| Interest Paid Monthly [Member]
Debt Instrument, Interest Rate, Stated Percentage	5.50%
American Ag Credit Term Loan [Member]
Long-term Debt	$ 14,697,000	$ 14,697,000
Debt Instrument, Interest Rate, Stated Percentage	7.00%	7.00%
Pledged Assets not Separately Reported Area of Real Estate \| a	3,700
Debt Instrument, Mandatory Principal Repayments as Percentage Net Proceeds of Sale of Real Estate Property Pledged as Collateral	100.00%
Minimum [Member]
Debt Instrument, Covenant Required Liquidity	$ 3,000,000
Maximum [Member]
Debt Instrument, Covenant Required Liquidity	175,000,000
Long-term Debt	$ 40,565,000	$ 40,565,000

Represents the amount of liabilities required to be maintained under financial covenants.

No definition available.

Name:	mlp_DebtInstrumentCovenantRequiredLiabilities
Namespace Prefix:	mlp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the amount of liquidity required to be maintained under financial covenants.

+ References

No definition available.

+ Details

Name:	mlp_DebtInstrumentCovenantRequiredLiquidity
Namespace Prefix:	mlp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the amount of mandatory principal repayment as a percentage of the net proceeds of the sale of non-collateralized real property.

+ References

No definition available.

+ Details

Name:	mlp_DebtInstrumentMandatoryPrincipalRepaymentsAsPercentageNetProceedsOfSaleOfNonCollateralizedRealProperty
Namespace Prefix:	mlp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the amount of mandatory principal repayment as a percentage of the net proceeds of the sale of any real property pledged as collateral.

+ References

No definition available.

+ Details

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Namespace Prefix:	mlp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The maximum principal amount outstanding to trigger reduction in interest rate.

+ References

No definition available.

+ Details

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Namespace Prefix:	mlp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Area of real estate owned but transferred to serve as collateral for the payment of the related debt obligation, primarily a secured borrowing or repurchase agreement, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.

+ References

No definition available.

+ Details

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Namespace Prefix:	mlp_
Data Type:	num:areaItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentInterestRateIncreaseDecrease
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ 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)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of the fee for available but unused credit capacity under the credit facility.

+ 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 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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.

+ 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 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: 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))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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 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

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_LongtermDebtTypeAxis=mlp_WellsFargoRevolvingLoansMember
Namespace Prefix:
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Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
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- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
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Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=mlp_FirstHawaiianBankRevolvingLineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=mlp_AmericanAgCreditTermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=mlp_InterestPaidMonthlyMember
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Data Type:	na
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