Derivative Instruments - Additional Information (Detail) gal in Thousands, $ in Thousands	6 Months Ended	12 Months Ended
Jun. 30, 2017 USD ($) $ / gal gal	Dec. 31, 2016 USD ($) $ / gal gal
Derivative [Line Items]
Energy Marketing Contracts Assets, Current	$ 229	$ 823
Number of Years for Asset Management Agreement	3 years
Energy Marketing Contract Liabilities, Current	$ (188)	(773)
Natural Gas Futures [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume \| gal	243
Propane Swap Agreement [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume \| gal	4,800
Designated as Hedging Instrument [Member] \| Mark To Market Energy Assets [Member] \| Natural Gas Futures [Member]
Derivative [Line Items]
Energy Marketing Contracts Assets, Current	$ 128	113
Designated as Hedging Instrument [Member] \| Mark To Market Energy Assets [Member] \| Propane Swap Agreement [Member]
Derivative [Line Items]
Energy Marketing Contracts Assets, Current	97	693
Designated as Hedging Instrument [Member] \| Mark To Market Energy Assets [Member] \| Put Option [Member]
Derivative [Line Items]
Energy Marketing Contracts Assets, Current	0	9
Designated as Hedging Instrument [Member] \| Mark To Market Energy Liabilities [Member] \| Propane Swap Agreement [Member]
Derivative [Line Items]
Energy Marketing Contract Liabilities, Current	(177)	0
Not Designated as Hedging Instrument [Member] \| Mark To Market Energy Assets [Member] \| Natural Gas Futures [Member]
Derivative [Line Items]
Energy Marketing Contracts Assets, Current	127
Not Designated as Hedging Instrument [Member] \| Mark To Market Energy Assets [Member] \| Propane Swap Agreement [Member]
Derivative [Line Items]
Energy Marketing Contracts Assets, Current	4	8
Not Designated as Hedging Instrument [Member] \| Mark To Market Energy Liabilities [Member] \| Natural Gas Futures [Member]
Derivative [Line Items]
Energy Marketing Contract Liabilities, Current	$ (11)	$ (773)
PESCO [Member] \| Natural Gas Futures [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume \| gal	2,600
Derivative, Term of Contract	2 years
PESCO [Member] \| Designated as Hedging Instrument [Member] \| Natural Gas Futures [Member]
Derivative [Line Items]
Energy Marketing Contract Liabilities, Current	$ (11)
Sharp Energy Inc [Member] \| Put Option [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume \| gal		630
Payments for Derivative Instrument, Financing Activities		$ 33
Sharp Energy Inc [Member] \| Put Option Strike Price 1 [Member] \| Put Option [Member]
Derivative [Line Items]
Derivative, Price Risk Option Strike Price \| $ / gal		0.5650
2017 [Member] \| Propane Swap Agreement [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume \| gal	6,300
2017 [Member] \| Mark To Market Energy Assets [Member] \| Propane [Member]
Derivative [Line Items]
Energy Marketing Contracts Assets, Current	$ 30
2017 [Member] \| Strike Price 4 [Member] \| Propane Swap Agreement [Member]
Derivative [Line Items]
Strike Price Per Gallon For The Propane Swap Agreements \| $ / gal	0.5975
2017 [Member] \| Strike Price 2 [Member] \| Propane Swap Agreement [Member]
Derivative [Line Items]
Strike Price Per Gallon For The Propane Swap Agreements \| $ / gal	0.7025
2016 [Member] \| Propane Swap Agreement [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume \| gal	720
2016 [Member] \| Strike Price 4 [Member] \| Propane Swap Agreement [Member]
Derivative [Line Items]
Strike Price Per Gallon For The Propane Swap Agreements \| $ / gal	0.5225
2016 [Member] \| Strike Price 2 [Member] \| Propane Swap Agreement [Member]
Derivative [Line Items]
Strike Price Per Gallon For The Propane Swap Agreements \| $ / gal	0.5650
2016 [Member] \| Designated as Hedging Instrument [Member] \| Mark To Market Energy Assets [Member] \| Propane Swap Agreement [Member]
Derivative [Line Items]
Energy Marketing Contracts Assets, Current	$ 67

Number of Years for Asset Management Agreement

No definition available.

Name:	cpk_NumberofYearsforAssetManagementAgreement
Namespace Prefix:	cpk_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Strike Price Per Gallon For The Propane Swap Agreements

+ References

No definition available.

+ Details

Name:	cpk_StrikePricePerGallonForThePropaneSwapAgreements
Namespace Prefix:	cpk_
Data Type:	us-types:perUnitItemType
Balance Type:	na
Period Type:	instant

- 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_DerivativeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Nominal volume used to calculate payments on a derivative instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeNonmonetaryNotionalAmountVolume
Namespace Prefix:	us-gaap_
Data Type:	num:volumeItemType
Balance Type:	na
Period Type:	duration

- Definition

The strike price on the price risk option contract such as a put option or a call option.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativePriceRiskOptionStrikePrice
Namespace Prefix:	us-gaap_
Data Type:	us-types:perUnitItemType
Balance Type:	na
Period Type:	instant

- Definition

Period the derivative contract is outstanding, 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_DerivativeTermOfContract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Current liabilities attributable to energy marketing activities (trading activities). Current energy marketing (trading activities) are when entities engage in both financial and physical trading to increase profits, manage their commodity price risk and enhance system reliability. They may trade electricity, coal, natural gas and oil. These entities typically use a variety of financial instruments, including forward contracts, options and swaps.

+ 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 210.5-02.20)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Carrying amount as of the balance sheet date of the asset arising from energy trading activities that involves the purchase and sale of energy under forward contracts at fixed and variable prices and the buying and selling of financial energy contracts that include exchange futures and options and over the counter options and swaps, which are expected to be converted into cash or otherwise disposed of within a year or the normal operating cycle, if longer.

+ 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 210.5-02.2)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_EnergyMarketingContractsAssetsCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The cash outflow for derivative instruments during the period, which are classified as financing activities, excluding those designated as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 23
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3505-108585

+ Details

Name:	us-gaap_PaymentsForDerivativeInstrumentFinancingActivities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=cpk_NaturalGasFuturesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=cpk_PropaneSwapAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_HedgingDesignationAxis=us-gaap_DesignatedAsHedgingInstrumentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BalanceSheetLocationAxis=cpk_MarkToMarketEnergyAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_PutOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BalanceSheetLocationAxis=cpk_MarkToMarketEnergyLiabilitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_HedgingDesignationAxis=us-gaap_NondesignatedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=cpk_PESCOMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=cpk_SharpEnergyIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cpk_StrikePricesPropanePutOptionsAxis=cpk_PutOptionStrikePrice1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cpk_OriginationYearAxis=cpk_A2017Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=cpk_PropaneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cpk_StrikePricesPropaneSwapAgreementsAxis=cpk_StrikePrice1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cpk_StrikePricesPropaneSwapAgreementsAxis=cpk_StrikePrice2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cpk_OriginationYearAxis=cpk_A2016Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: