Fair Value Measurements (Estimated Fair Values of Financial Instruments) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Financial assets:
Cash and cash equivalents	$ 42,832	$ 44,996
Securities	847,961	849,620
Loans Held-for-sale, Fair Value Disclosure	5,037	6,371
Loans, net	1,980,846	1,734,609
Restricted investments in bank stock	15,223	20,564
Accrued interest receivable	7,349	7,059
Financial liabilities:
Deposits	2,383,085us-gaap_DepositsFairValueDisclosure	2,241,179us-gaap_DepositsFairValueDisclosure
Short-term borrowings	333,475	277,750
Long-term debt		12,642us-gaap_LongTermDebtFairValue
Accrued interest payable	325metr_InterestPayableFairValueDisclosure	218metr_InterestPayableFairValueDisclosure
Standby Letters of Credit [Member]
Financial liabilities:
Off-balance sheet instruments	0	0
Commitments to Extend Credit [Member]
Financial liabilities:
Off-balance sheet instruments	0	0
Fair Value, Inputs, Level 1 [Member]
Financial assets:
Cash and cash equivalents	42,832	44,996
Securities	0	0
Loans Held-for-sale, Fair Value Disclosure	0	0
Loans, net	0	0
Restricted investments in bank stock	0	0
Accrued interest receivable	7,349	7,059
Financial liabilities:
Deposits	0	0
Short-term borrowings	333,475	277,750
Long-term debt		0
Accrued interest payable	325	218
Fair Value, Inputs, Level 1 [Member] \| Standby Letters of Credit [Member]
Financial liabilities:
Off-balance sheet instruments	0	0
Fair Value, Inputs, Level 1 [Member] \| Commitments to Extend Credit [Member]
Financial liabilities:
Off-balance sheet instruments	0	0
Fair Value, Inputs, Level 2 [Member]
Financial assets:
Cash and cash equivalents	0	0
Securities	847,961	849,620
Loans Held-for-sale, Fair Value Disclosure	0	0
Loans, net	0	0
Restricted investments in bank stock	0	0
Accrued interest receivable	0	0
Financial liabilities:
Deposits	0	0
Short-term borrowings	0	0
Long-term debt		0
Accrued interest payable	0	0
Fair Value, Inputs, Level 2 [Member] \| Standby Letters of Credit [Member]
Financial liabilities:
Off-balance sheet instruments	0	0
Fair Value, Inputs, Level 2 [Member] \| Commitments to Extend Credit [Member]
Financial liabilities:
Off-balance sheet instruments	0	0
Fair value inputs, Level 3 [Member]
Financial assets:
Cash and cash equivalents	0	0
Securities	0	0
Loans Held-for-sale, Fair Value Disclosure	5,037	6,371
Loans, net	1,980,846	1,734,609
Restricted investments in bank stock	15,223	20,564
Accrued interest receivable	0	0
Financial liabilities:
Deposits	2,383,085	2,241,179
Short-term borrowings	0	0
Long-term debt		12,642
Accrued interest payable	0	0
Fair value inputs, Level 3 [Member] \| Standby Letters of Credit [Member]
Financial liabilities:
Off-balance sheet instruments	0	0
Fair value inputs, Level 3 [Member] \| Commitments to Extend Credit [Member]
Financial liabilities:
Off-balance sheet instruments	0	0
Carrying Amount [Member]
Financial assets:
Cash and cash equivalents	42,832	44,996
Securities	853,032	869,737
Loans Held-for-sale, Fair Value Disclosure	4,996	6,225
Loans, net	1,973,536	1,727,762
Restricted investments in bank stock	15,223	20,564
Accrued interest receivable	7,349	7,059
Financial liabilities:
Deposits	2,380,672	2,239,621
Short-term borrowings	333,475	277,750
Long-term debt		15,800
Accrued interest payable	325	218
Carrying Amount [Member] \| Standby Letters of Credit [Member]
Financial liabilities:
Off-balance sheet instruments	0	0
Carrying Amount [Member] \| Commitments to Extend Credit [Member]
Financial liabilities:
Off-balance sheet instruments	$ 0	$ 0

Interest Payable, Fair Value Disclosure

No definition available.

Name:	metr_InterestPayableFairValueDisclosure
Namespace Prefix:	metr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Interest Receivable, Fair Value Disclosure

+ References

No definition available.

+ Details

Name:	metr_InterestReceivableFairValueDisclosure
Namespace Prefix:	metr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Marketable Securities, Fair Value Disclosure

+ References

No definition available.

+ Details

Name:	metr_MarketableSecuritiesFairValueDisclosure
Namespace Prefix:	metr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Restricted Investments in Bank Stock, Fair Value Disclosure

+ References

No definition available.

+ Details

Name:	metr_RestrictedInvestmentsInBankStockFairValueDisclosure
Namespace Prefix:	metr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Short-term Borrowing and Repurchase Agreements, Fair Value Disclosure

+ References

No definition available.

+ Details

Name:	metr_ShortTermBorrowingAndRepurchaseAgreementsFairValueDisclosure
Namespace Prefix:	metr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Cash

-URI http://asc.fasb.org/extlink&oid=6506951

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Cash Equivalents

-URI http://asc.fasb.org/extlink&oid=6507016

+ Details

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

- Definition

Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

+ References

No definition available.

+ Details

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

- Definition

The fair value of financial liabilities, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13433-108611

+ Details

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

- Details

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

- Details

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

- Definition

Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

+ References

No definition available.

+ Details

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

- Definition

Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Glossary Loan

-URI http://asc.fasb.org/extlink&oid=6517073

+ Details

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

- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByMeasurementBasisAxis=us-gaap_CarryingReportedAmountFairValueDisclosureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CommitmentsToExtendCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=us-gaap_FinancialStandbyLetterOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: