TRANSACTIONS WITH AFFILIATES (Details) (EMC Reinsurance [Member], USD $)	3 Months Ended	12 Months Ended
Mar. 31, 2013	Dec. 31, 2012
EMC Reinsurance [Member]
Related Party Transaction [Line Items]
Catastrophe claims, retention amount	$ 4,000,000	$ 4,000,000
Percentage as cost of protection to assumed reinsurance premiums written (in hundredths)	9.00%	10.00%
First layer excess of loss coinsurance percentage (in hundredths)	20.00%
First layer excess of loss limit	10,000,000
Second layer excess of loss coinsurance percentage (in hundredths)	10.00%
Second layer excess of loss limit	$ 50,000,000

The Company's coinsurance percentage specified for the first layer in a ceded reinsurance contract between the Company and an affiliate.

No definition available.

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

The Company's limit specified for the first layer in a ceded reinsurance contract between the Company and an affiliate.

No definition available.

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

The Company's retention amount specified in a ceded reinsurance contract between the Company and an affiliate.

No definition available.

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

The Company's coinsurance percentage specified for the second layer in a ceded reinsurance contract between the Company and an affiliate.

No definition available.

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

The Company's limit specified for the second layer in a ceded reinsurance contract between the Company and an affiliate.

No definition available.

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

Refers to percentage of cost of protection to total assumed reinsurance premiums written under an affiliated ceded reinsurance contract.

No definition available.

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

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