REINSURANCE (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014 reinsurer	Dec. 31, 2013 reinsurer	Dec. 31, 2012
Reinsurance Transactions For Insurance Companies, by Product Segment [Line Items]
Number of significant nonaffiliated reinsurers	3emci_NumberOfNonaffiliatedReinsurers	4emci_NumberOfNonaffiliatedReinsurers
Total receivable amount from significant nonaffiliated reinsurers	$ 16,308	$ 24,261
Number Of Mandatory Nonaffiliated Reinsurers	1	2
Percentage of pool participation (in hundredths)	30.00%emci_PercentageOfPoolParticipation	30.00%emci_PercentageOfPoolParticipation	30.00%emci_PercentageOfPoolParticipation
Premiums written
Net premiums written	552,610us-gaap_PremiumsWrittenNet	534,077us-gaap_PremiumsWrittenNet	478,481us-gaap_PremiumsWrittenNet
Premiums earned
Direct	372,658us-gaap_DirectPremiumsEarned	361,010us-gaap_DirectPremiumsEarned	328,227us-gaap_DirectPremiumsEarned
Assumed	591,666us-gaap_AssumedPremiumsEarned	567,918us-gaap_AssumedPremiumsEarned	499,489us-gaap_AssumedPremiumsEarned
Ceded	(423,602)us-gaap_CededPremiumsEarned	(413,422)us-gaap_CededPremiumsEarned	(368,870)us-gaap_CededPremiumsEarned
Net premiums earned	540,722	515,506	458,846
Losses and settlement expenses incurred
Net losses and settlement expenses incurred	385,474	333,287	303,388
Affiliated Entity [Member]
Premiums written
Assumed	455,183	425,218	390,982
Ceded	(378,071)	(381,293)	(353,222)
Premiums earned
Assumed	443,440	412,665	377,690
Ceded	(382,997)	(373,771)	(340,143)
Losses and settlement expenses incurred
Assumed	305,857	268,491	238,685
Ceded	(226,662)	(237,932)	(201,208)
Non Affiliated Entity [Member]
Premiums written
Direct	367,732	368,532	341,306
Assumed	147,519	165,792	123,959
Ceded	(39,753)	(44,172)	(24,544)
Premiums earned
Direct	372,658	361,010	328,227
Assumed	148,226	155,253	121,799
Ceded	(40,605)	(39,651)	(28,727)
Losses and settlement expenses incurred
Direct	227,382	237,109	191,282
Assumed	98,482	83,135	85,706
Ceded	(19,585)	(17,516)	(11,077)
Property and casualty insurance [Member]
Reinsurance Transactions For Insurance Companies, by Product Segment [Line Items]
Percentage of pool participation (in hundredths)	30.00%	30.00%	30.00%
Premiums written
Net premiums written	433,707	405,049	371,235
Premiums earned
Net premiums earned	422,381	392,719	357,139
Losses and settlement expenses incurred
Net losses and settlement expenses incurred	298,033	260,917	233,892
Property and casualty insurance [Member] \| Affiliated Entity [Member]
Reinsurance Transactions For Insurance Companies, by Product Segment [Line Items]
Percentage of pool participation (in hundredths)	30.00%	30.00%	30.00%
Premiums written
Assumed	455,183	425,218	390,982
Ceded	(367,732)	(368,532)	(341,306)
Premiums earned
Assumed	443,440	412,665	377,690
Ceded	(372,658)	(361,010)	(328,227)
Losses and settlement expenses incurred
Assumed	304,579	267,292	237,723
Ceded	(227,382)	(237,109)	(191,282)
Property and casualty insurance [Member] \| Non Affiliated Entity [Member]
Premiums written
Direct	367,732	368,532	341,306
Assumed	3,955	3,501	2,459
Ceded	(25,431)	(23,670)	(22,206)
Premiums earned
Direct	372,658	361,010	328,227
Assumed	3,787	3,275	2,297
Ceded	(24,846)	(23,221)	(22,848)
Losses and settlement expenses incurred
Direct	227,382	237,109	191,282
Assumed	2,201	2,281	1,718
Ceded	(8,747)	(8,656)	(5,549)
Reinsurance [Member]
Premiums written
Net premiums written	118,903	129,028	107,246
Premiums earned
Net premiums earned	118,341	122,787	101,707
Losses and settlement expenses incurred
Net losses and settlement expenses incurred	87,441	72,370	69,496
Reinsurance [Member] \| Affiliated Entity [Member]
Premiums written
Assumed	0	0	0
Ceded	(10,339)	(12,761)	(11,916)
Premiums earned
Assumed	0	0	0
Ceded	(10,339)	(12,761)	(11,916)
Losses and settlement expenses incurred
Assumed	1,278	1,199	962
Ceded	720	(823)	(9,926)
Reinsurance [Member] \| Non Affiliated Entity [Member]
Premiums written
Direct	0	0	0
Assumed	143,564	162,291	121,500
Ceded	(14,322)	(20,502)	(2,338)
Premiums earned
Direct	0	0	0
Assumed	144,439	151,978	119,502
Ceded	(15,759)	(16,430)	(5,879)
Losses and settlement expenses incurred
Direct	0	0	0
Assumed	96,281	80,854	83,988
Ceded	$ (10,838)	$ (8,860)	$ (5,528)

Refers to the number of mandatory nonaffiliated reinsurers from which the Company has significant amounts recoverable.

No definition available.

Name:	emci_NumberOfMandatoryNonaffiliatedReinsurers
Namespace Prefix:	emci_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Refers to the number of nonaffiliated reinsurers from which the Company has significant amounts recoverable.

+ References

No definition available.

+ Details

Name:	emci_NumberOfNonaffiliatedReinsurers
Namespace Prefix:	emci_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Refers to percentage of pool participation for the property and casualty insurance subsidiaries.

+ References

No definition available.

+ Details

Name:	emci_PercentageOfPoolParticipation
Namespace Prefix:	emci_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	emci_ReinsuranceTransactionsForInsuranceCompaniesByProductSegmentLineItems
Namespace Prefix:	emci_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Refers to the amount receivable from nonaffiliated reinsurers from which the Company has significant amounts recoverable.

+ References

No definition available.

+ Details

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

- Definition

Amount of earned premiums assumed from other entities.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 17

-Article 12

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 235

-Section S99

-Paragraph 2

-Subparagraph (SX 210.12-17)

-URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e574992-122915

Reference 3: 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 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)(2)

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

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 1

-Article 7

+ Details

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

- Definition

Amount of written premiums assumed from other entities.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 605

-Section 50

-Paragraph 1

-Subparagraph (b)(2),(c)(2)

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

+ Details

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

- Definition

Amount of earned premiums ceded to other entities.

+ References

+ Details

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

- Definition

Amount of written premiums ceded to other entities.

+ References

+ Details

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

- Definition

Amount, before premiums ceded to other entities and premiums assumed by the entity, of premiums earned.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 17

-Article 12

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 235

-Section S99

-Paragraph 2

-Subparagraph (SX 210.12-17)

-URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e574992-122915

Reference 3: 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 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 1

-Article 7

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 605

-Section 50

-Paragraph 1

-Subparagraph (b),(c)(1)

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

+ Details

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

- Definition

Amount, before premiums ceded to other entities and premiums assumed by the entity, of premiums written.

+ References

+ Details

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

- Definition

Amount, before effect of policies assumed or ceded, of expense related to provision for policy benefits and costs incurred.

+ References

+ Details

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

- Definition

Amount, after effects of policies assumed or ceded, of expense related to the provision for policy benefits and costs incurred.

+ 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 210.7-04.5)

-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 5

-Article 7

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 20

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6480758&loc=d3e6811-158387

+ Details

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

- Details

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

- Definition

Amount, after premiums ceded to other entities and premiums assumed by the entity, of premiums written.

+ References

+ Details

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

- Details

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

- Definition

Amount of policy benefits and costs incurred for policies assumed.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 20

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6480758&loc=d3e6811-158387

+ Details

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

- Definition

Amount of reduction of provision for policy benefits and costs incurred for policies ceded.

+ References

+ Details

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

- Details

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

- Details

Name:	dei_LegalEntityAxis=us-gaap_AffiliatedEntityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=emci_ReinsuranceMember
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: