SEGMENT INFORMATION - Summarized financial information by segment (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Reconciliation of operating profit loss from segment to consolidated
Premiums earned	$ 138,731	$ 133,080
Underwriting profit (loss)	17,084emci_UnderwritingProfitLoss	2,350emci_UnderwritingProfitLoss
Net investment income (loss)	11,206us-gaap_NetInvestmentIncome	11,855us-gaap_NetInvestmentIncome
Realized investment gains	783us-gaap_GainLossOnInvestments	1,262us-gaap_GainLossOnInvestments
Other income (loss)	1,615us-gaap_OtherIncome	34us-gaap_OtherIncome
Interest expense	84emci_InterestExpenseToAffiliates	84emci_InterestExpenseToAffiliates
Other expenses	667us-gaap_OtherCostAndExpenseOperating	528us-gaap_OtherCostAndExpenseOperating
Income before income tax expense	29,937	14,889
Reconciliation of assets from segment to consolidated
Assets	2,033,779		1,994,576
Eliminations	(518,915)emci_AssetsEliminations		(495,288)emci_AssetsEliminations
Reclassifications	(905)emci_AssetsReclassifications		(1,468)emci_AssetsReclassifications
Total assets	1,513,959us-gaap_Assets		1,497,820us-gaap_Assets
Property and casualty insurance [Member]
Reconciliation of operating profit loss from segment to consolidated
Premiums earned	108,205	101,247
Underwriting profit (loss)	14,078	(475)
Net investment income (loss)	8,026	8,616
Realized investment gains	700	1,011
Other income (loss)	182	201
Interest expense	84	84
Other expenses	206	174
Income before income tax expense	22,696	9,095
Reconciliation of assets from segment to consolidated
Assets	1,066,912		1,057,429
Eliminations	0		0
Reclassifications	0		(909)
Total assets	1,066,912		1,056,520
Reinsurance [Member]
Reconciliation of operating profit loss from segment to consolidated
Premiums earned	30,526	31,833
Underwriting profit (loss)	3,006	2,825
Net investment income (loss)	3,184	3,243
Realized investment gains	83	251
Other income (loss)	1,433	(167)
Interest expense	0	0
Other expenses	0	0
Income before income tax expense	7,706	6,152
Reconciliation of assets from segment to consolidated
Assets	439,382		434,139
Eliminations	0		0
Reclassifications	0		0
Total assets	439,382		434,139
Parent company [Member]
Reconciliation of operating profit loss from segment to consolidated
Premiums earned	0	0
Underwriting profit (loss)	0	0
Net investment income (loss)	(4)	(4)
Realized investment gains	0	0
Other income (loss)	0	0
Interest expense	0	0
Other expenses	461	354
Income before income tax expense	(465)	(358)
Reconciliation of assets from segment to consolidated
Assets	527,485		503,008
Eliminations	(518,915)		(495,288)
Reclassifications	(905)		(559)
Total assets	$ 7,665		$ 7,161

Refers to assets before elimination and reclassification.

No definition available.

Name:	emci_AssetsBeforeEliminationAndReclassification
Namespace Prefix:	emci_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

For consolidation, the elimination of the parent company's ownership amount in the subsidiaries included in the consolidation.

+ References

No definition available.

+ Details

Name:	emci_AssetsEliminations
Namespace Prefix:	emci_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

For consolidation, the reclassification of the various subsidiaries' asset and liability amounts relating to common transactions.

+ References

No definition available.

+ Details

Name:	emci_AssetsReclassifications
Namespace Prefix:	emci_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The cost of borrowed funds from affiliates accounted for as interest that was charged against earnings during the period.

+ References

No definition available.

+ Details

Name:	emci_InterestExpenseToAffiliates
Namespace Prefix:	emci_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Aggregate premium revenue less insurance benefit costs including losses, settlement expenses, acquisition costs amortized, policyholder dividends, and other underwriting expenses.

+ References

No definition available.

+ Details

Name:	emci_UnderwritingProfitLoss
Namespace Prefix:	emci_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ 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 210.5-02.18)

-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 210

-SubTopic 10

-Section S99

-Paragraph 1

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

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 12

-Article 7

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 18

-Article 5

+ Details

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

- Definition

This item represents the net total realized and unrealized gain (loss) included in earnings for the period as a result of selling or holding marketable securities categorized as trading, available-for-sale, or held-to-maturity, including the unrealized holding gain (loss) of held-to-maturity securities transferred to the trading security category and the cumulative unrealized gain (loss) which was included in other comprehensive income (a separate component of shareholders' equity) for available-for-sale securities transferred to trading securities during the period. Additionally, this item would include any gains (losses) realized during the period from the sale of investments accounted for under the cost method of accounting and losses recognized for other than temporary impairments (OTTI) of the subject investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.7(c),9(a))

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27405-111563

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 9

-Subparagraph (c)-(e)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27357-111563

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 7

-Article 5

+ Details

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

- Definition

Sum of operating profit and nonoperating income or expense before Income or Loss from equity method investments, income taxes, extraordinary items, and noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(h)(1)(i))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

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

- Definition

Amount, after investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 16

-Article 12

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-04.2)

-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 2

-Article 7

+ Details

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

- Definition

The total amount of other operating cost and expense items that are associated with the entity's normal revenue producing operation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.3)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 3

-Article 5

+ Details

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

- Definition

Reflects the sum of all other revenue and income recognized by the entity in the period not otherwise specified in the income statement.

+ References

+ Details

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

- Definition

Amount, after premiums ceded to other entities and premiums assumed by the entity, of property and casualty premiums earned.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-04.1)

-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 1

-Article 7

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 605

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6486662&loc=d3e27175-158546

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 605

-Section 50

-Paragraph 1

-Subparagraph (b),(c)

-URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547

+ Details

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

- Details

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

- Details

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

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=emci_ReinsuranceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=us-gaap_ParentCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=us-gaap_PropertyLiabilityAndCasualtyInsuranceSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: