2.4.0.82030 - Disclosure - Summary of Significant Accounting Policies (Policies)truefalsefalse1false falsefalseD2013Q2YTDhttp://www.sec.gov/CIK0001465885duration2013-01-01T00:00:002013-06-30T00:00:001true 1us-gaap_AccountingPoliciesAbstractus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Summary of Significant Accounting Policies2false 2us-gaap_BasisOfAccountingPolicyPolicyTextBlockus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00<div style="font-size:10.0pt;font-family:Times New Roman;"> Basis of Presentation   The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (“GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting periods.  Actual results could differ from those estimates.   In the opinion of management, all adjustments (which include only normal recurring adjustments) necessary have been made to present fairly the Company’s financial position, results of operations and cash flows.  Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted in accordance with Article 10 of Regulation S-X and the instructions to Form 10-Q.  These financial statements should be read in conjunction with the Company’s annual report on Form 10-K for the year ended December 31, 2012, filed with the Securities and Exchange Commission (“SEC”) on April 9, 2013.  The results of operations for the period ended June 30, 2013 are not necessarily indicative of the results to be expected for the full year or any future period.   The Company currently operates as one business segment. </div>falsefalsefalsenonnum:textBlockItemTypenaDisclosure of accounting policy for basis of accounting, or basis of presentation, used to prepare the financial statements (for example, US Generally Accepted Accounting Principles, Other Comprehensive Basis of Accounting, IFRS).No definition available.false0Basis of Presentation3false 2us-gaap_CashAndCashEquivalentsUnrestrictedCashAndCashEquivalentsPolicyus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00<div style="font-size:10.0pt;font-family:Times New Roman;"> Cash and Cash Equivalents   The Company considers all highly-liquid short term investments with original maturities of 90 days or less when purchased to be cash equivalents.  Cash and cash equivalents are exposed to concentrations of credit risk. The Company places its cash and cash equivalents with what it believes to be high credit quality institutions. At times such investments may be in excess of the Federal Deposit Insurance Corporation insurance limit. </div>falsefalsefalsenonnum:textBlockItemTypenaDisclosure of accounting policy for cash and cash equivalents with respect to unrestricted balances.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6367646&loc=d3e18780-107790 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Cash -URI http://asc.fasb.org/extlink&oid=6506951 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Cash Equivalents -URI http://asc.fasb.org/extlink&oid=6507016 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4273-108586 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 305 -SubTopic 10 -URI http://asc.fasb.org/subtopic&trid=2122427 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Technical Practice Aid (TPA) -Number 2110 -Paragraph 6 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 7, 8, 9, 10 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false0Cash and Cash Equivalents4false 2wmc_MortgageBackedAndUSTreasurySecuritiesFairValueOptionPolicyTextBlockwmc_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00<div style="font-size:10.0pt;font-family:Times New Roman;"> Mortgage-backed and US Treasury securities - Fair value election   The Company has elected the fair value option for all of its RMBS and US Treasury securities at the date of purchase, which permits the Company to measure these securities at fair value with the change in fair value included as a component of earnings. In the Manager’s view, this election more appropriately reflects the results of the Company’s operations for a particular reporting period, as financial asset fair value changes are presented in a manner consistent with the presentation and timing of the fair value changes of economic hedging instruments. </div>falsefalsefalsenonnum:textBlockItemTypenaDisclosure of the accounting policy related to the fair value option election of mortgage-backed and US Treasury securities.No definition available.false0Mortgage-backed and US Treasury securities - Fair value election5false 2wmc_MortgageBackedSecuritiesBalanceSheetPresentationPolicyTextBlockwmc_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00<div style="font-size:10.0pt;font-family:Times New Roman;"> Balance Sheet Presentation   The Company’s mortgage-backed securities purchases and sales are recorded on the trade date, which results in an investment related payable (receivable) for RMBS purchased (sold) for which settlement has not taken place as of the balance sheet date. The Company’s RMBS pledged as collateral against borrowings under repurchase agreements, and that are not accounted for as linked transactions, described below, are included in residential mortgage-backed securities on the Balance Sheets, with the fair value of such securities pledged disclosed parenthetically. </div>falsefalsefalsenonnum:textBlockItemTypenaDisclosure of the accounting policy related to the balance sheet presentation of mortgage-backed securities.No definition available.false0Balance Sheet Presentation6false 2us-gaap_FairValueOfFinancialInstrumentsPolicyus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00<div style="font-size:10.0pt;font-family:Times New Roman;FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt;"> Valuation of financial instruments   The Company discloses the fair value of its financial instruments according to a fair value hierarchy (Levels I, II, and III, as defined below). In accordance with GAAP, the Company is required to provide enhanced disclosures regarding instruments in the Level III category (which require significant management judgment), including a separate reconciliation of the beginning and ending balances for each major category of assets and liabilities.  GAAP establishes a framework for measuring fair value and expands financial statement disclosure requirements for fair value measurements. GAAP further specifies a hierarchy of valuation techniques, which is based on whether the inputs into the valuation technique are observable or unobservable. The hierarchy is as follows:   Level I — Quoted prices in active markets for identical assets or liabilities.   Level II — Quoted prices for similar assets and liabilities in active markets; quoted prices for identical or similar instruments in markets that are not active; and model-derived valuations whose inputs are observable or whose significant value drivers are observable.   Level III — Prices are determined using significant unobservable inputs. In situations where quoted prices or observable inputs are unavailable, for example, when there is little or no market activity for an investment at the end of the period, unobservable inputs may be used.   The level in the fair value hierarchy within which a fair measurement in its entirety falls is based on the lowest level input that is significant to the fair value measurement in its entirety.   When available, the Company uses quoted market prices to determine the fair value of an asset or liability. If quoted market prices are not available, the Company consults with independent pricing services or obtains third party broker quotes. If independent pricing service, or third party broker quotes are not available, the Company determines the fair value of the securities using valuation techniques that use, when possible, current market-based or independently-sourced market parameters, such as interest rates and when applicable, estimates of prepayment and credit losses.   Valuation techniques for RMBS may be based upon models that consider the estimated cash flows of the security. The primary inputs to the model include yields for to-be-announced, also known as TBAs, Agency RMBS, the U.S. Treasury market and floating rate indices such as LIBOR, the Constant Maturity Treasury rate and the prime rate as a benchmark yield. The model incorporates the current weighted average maturity and additional pool level information such as prepayment speeds, default frequencies and default severities, if applicable. To the extent, the inputs are observable and timely, the values are categorized in Level II of the fair value hierarchy; otherwise they would be categorized as Level III.   While linked transactions, described below, are treated as derivatives for GAAP, the securities underlying the Company’s linked transactions are valued using similar techniques to those used for the Company’s securities portfolio. The value of the underlying security is then netted against the carrying amount (which approximates fair value) of the repurchase agreement at the valuation date. Additionally, TBA instruments are similar in substance to the Company’s Agency RMBS portfolio, and the Company therefore estimates fair value based on similar methods.   The Company determines the fair value of derivative financial instruments by obtaining quotes from a third party pricing service, whose pricing is subject to review by the Manager’s pricing committee. In valuing its interest rate derivatives, such as swaps and swaptions, the Company considers the creditworthiness of both the Company and its counterparties, along with collateral provisions contained in each derivative agreement, from the perspective of both the Company and its counterparties. All of the Company’s interest rate swaps are either cleared through a central clearinghouse and subject to the clearinghouse margin requirements or subject to bilateral collateral arrangements. The Company also has netting arrangements in place with all derivative counterparties pursuant to standard documentation developed by the International Swap and Derivatives Association. Consequently, no credit valuation adjustment was made in determining the fair value of interest rate derivatives.   In May 2011, the Financial Accounting Standards Board or FASB issued amendments, which were adopted by the Company, to achieve common fair value measurement and disclosure requirements in GAAP and International Financial Reporting Standards. New disclosures, with a particular focus on Level III measurement are required. All transfers between Level I and Level II are required to be disclosed. There were no transfers between hierarchy levels during operations for the six months ended June 30, 2013.  Information about when the current use of a non-financial asset measured at fair value differs from its highest and best use is to be disclosed.   Fair value under GAAP represents an exit price in the normal course of business, not a forced liquidation price. If the Company is forced to sell assets in a short period to meet liquidity needs, the prices it receives can be substantially less than their recorded fair values. Furthermore, the analysis of whether it is more likely than not that the Company will be required to sell securities in an unrealized loss position prior to an expected recovery in value (if any), the amount of such expected required sales, and the projected identification of which securities will be sold is also subject to significant judgment, particularly in times of market illiquidity.   Any changes to the valuation methodology will be reviewed by the Company and its Manager to ensure the changes are appropriate. As markets and products develop and the pricing for certain products becomes more transparent, the Company will continue to refine its valuation methodologies. The Company utilizes and follows the pricing methodology employed by its Manager, including its review and challenge process.  The methods used by the Company may produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. Furthermore, while the Company anticipates that its valuation methods will be appropriate and consistent with other market participants, the use of different methodologies, or assumptions, to determine the fair value of certain financial instruments can result in a different estimate of fair value at the reporting date. The Company uses inputs that are current as of the measurement date, which may include periods of market dislocation, during which price transparency may be reduced.</div>falsefalsefalsenonnum:textBlockItemTypenaDisclosure of accounting policy for determining the fair value of financial instruments.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6367646&loc=d3e18780-107790 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -URI http://asc.fasb.org/subtopic&trid=2155942 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 107 -Paragraph 8, 10, 12, 13, 14 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false0Valuation of financial instruments7false 2us-gaap_RevenueRecognitionInterestus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00<div style="font-size:10.0pt;font-family:Times New Roman;"> Interest income recognition and Impairment   Agency RMBS and Non-Agency RMBS rated AA and higher at the time of purchase   Interest income on mortgage-backed securities is accrued based on the respective outstanding principal balances and corresponding contractual terms. Premiums and discounts associated with Agency RMBS and Non-Agency RMBS rated AA and higher at the time of purchase, are amortized into interest income over the estimated life of such securities using the effective yield method. Adjustments to premium and discount amortization are made for actual prepayment activity.  The Company estimates prepayments at least quarterly for its securities and as a result, if prepayments increase (or are expected to increase), the Company will accelerate the rate of amortization on premiums or discounts and make a retrospective adjustment to historical amortization.  Alternatively, if prepayments decrease (or are expected to decrease) the Company will reduce the rate of amortization on the premiums or discounts and make a retrospective adjustment to historical amortization.   The Company assesses its Agency RMBS and Non-Agency RMBS rated AA and higher at the time of purchase for other-than-temporary impairment on at least a quarterly basis. When the fair value of an investment is less than its amortized cost at the balance sheet date of the reporting period for which impairment is assessed, the impairment is designated as either “temporary” or “other-than-temporary.” In deciding on whether or not a security is other than temporarily impaired, the Company considers several factors, including the nature of the investment, communications (if any) from the trustees of securitizations regarding the credit quality of the security, the severity and duration of the impairment, the cause of the impairment, and the Company’s intent that the Company can hold the security until recovery of its cost basis.   The determination as to whether an other-than-temporary impairment exists is subject to management estimates based on consideration of both factual information available at the time of assessment as well as the Company’s estimates of the future performance and projected amount and timing of cash flows expected to be collected on the security. As a result, the timing and amount of an other-than-temporary impairment constitutes an accounting estimate that may change materially over time.   Non-Agency RMBS that are purchased at a discount to par value and are rated below AA at the time of purchase and Agency Interest-Only Strips that are not classified as derivatives   Interest income on Non-Agency RMBS that are purchased at a discount to par value and are rated below AA at the time of purchase and Agency Interest-Only Strips that are not classified as derivatives are recognized based on the effective yield method.  The effective yield on these securities is based on the projected cash flows from each security, which is estimated based on the Company’s observation of the then current information and events and will include assumptions related to interest rates, prepayment rates and the timing and amount of credit losses.  On at least a quarterly basis, the Company reviews and, if appropriate, makes adjustments to its cash flow projections based on input and analysis received from external sources, internal models, and its judgment about interest rates, prepayment rates, the timing and amount of credit losses (if applicable), and other factors. Changes in cash flows from those originally projected, or from those estimated at the last evaluation, may result in a prospective change in the yield/interest income recognized on such securities. Actual maturities of the securities are affected by the contractual lives of the associated mortgage collateral, periodic payments of scheduled principal, and prepayments of principal. Therefore, actual maturities of the securities will generally be shorter than stated contractual maturities.   Based on the projected cash flow of the Non-Agency RMBS purchased at a discount to par value, the Company may designate a portion of such purchase discount as credit protection against future credit losses and, therefore, not accrete such amount into interest income.  The amount designated as credit discount may be adjusted over time, based on the actual performance of the security, its underlying collateral, actual and projected cash flow from such collateral, economic conditions and other factors.  If the performance of a security with a credit discount is more favorable than forecasted, a portion of the amount designated as credit discount may be accreted into interest income prospectively.   In addition, an other-than-temporary impairment is deemed to have occurred when there is an adverse change in the expected cash flows (principal or interest) to be received and the fair value of the security is less than its carrying amount. In determining whether an adverse change in cash flows occurred, the present value of the remaining cash flows, as estimated at the initial transaction date (or the last date previously revised), is compared to the present value of the expected cash flows at the current reporting date.  The estimated cash flows reflect those a “market participant” would use and are discounted at a rate equal to the current yield used to accrete interest income. These adjustments are reflected in the Company’s Statement of Operations as Other loss on Residential mortgage-backed securities.   The determination as to whether an other-than-temporary impairment exists is subject to management estimates based on consideration of both factual information available at the time of assessment as well as the Company’s estimates of the future performance and projected amount and timing of cash flows expected to be collected on the security. As a result, the timing and amount of an other-than-temporary impairment constitutes an accounting estimate that may change materially over time.   Certain of the Company’s RMBS that are in an unrealized loss position at June 30, 2013 are not considered other than temporarily impaired because the Company has no intent to sell these investments, it is more likely than not that the Company will not be required to sell the investment before recovery of its amortized cost basis and the Company is not required to sell the security for regulatory or other reasons. </div>falsefalsefalsenonnum:textBlockItemTypenaDisclosure of accounting policy for recognition of interest revenue. Disclosure may include the method of recognizing interest income on loan and trade receivables, the method of amortizing premiums or accreting discounts, and a statement about the policy for the treatment of related fees and costs, including the method of amortizing net deferred fees and costs.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6367646&loc=d3e18780-107790 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 13 -Section B -Paragraph Question 1 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 605 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 13.B.Q1) -URI http://asc.fasb.org/extlink&oid=6600647&loc=d3e214044-122780 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 605 -SubTopic 10 -URI http://asc.fasb.org/subtopic&trid=2197196 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 21 -Paragraph 11-15 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Emerging Issues Task Force (EITF) -Number D-10 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false0Interest income recognition and Impairment8false 2us-gaap_MarketableSecuritiesAvailableForSaleSecuritiesPolicyus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00<div style="font-size:10.0pt;font-family:Times New Roman;"> Sales of securities   Sales of securities are driven by the Company’s portfolio management process. The Company seeks to mitigate risks including those associated with prepayments and will opportunistically rotate the portfolio into securities the Company’s Manager believe have more favorable attributes. Strategies may also be employed to manage net capital gains, which need to be distributed for tax purposes. Realized gains or losses on sales of securities and derivatives, inclusive of linked transactions are included in the net realized gain line item on the Statement of Operations, and are recorded at the time of disposition. The cost of positions sold is calculated using the specific identification method. </div>falsefalsefalsenonnum:textBlockItemTypenaDisclosure of accounting policy for investments in debt and equity securities that are classified as available-for-sale. This policy also may describe the entity's accounting treatment for transfers between investment categories, how the entity determines whether impairments of available-for-sale securities are other than temporary, and how the fair values of such securities are determined.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6367646&loc=d3e18780-107790 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -URI http://asc.fasb.org/subtopic&trid=2196929 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 5 -Section M Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 2, 12 -Article 5 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 107 -Paragraph 10, 11 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 12, 13, 14, 15, 16 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number FAS115-1/124-1 -Paragraph 7, 8, 9, 13, 14, 15, 16, 17 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false0Sales of securities9false 2wmc_DueFromAndDueToCounterpartiesPolicyTextBlockwmc_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00<div style="font-size:10.0pt;font-family:Times New Roman;"> Due from counterparties/Due to counterparties   Due from counterparties represents cash posted with its counterparties as collateral for the Company’s interest rate swaps and repurchase agreements. Due to counterparties represents cash posted with the Company by its counterparties as collateral under the Company’s interest rate swaps, interest rate swaptions and repurchase agreements. In addition, Due to counterparties include non-cash collateral in which the Company has the obligation to return the collateral upon the Company either selling or pledging the non-cash collateral. Due from counterparties and Due to counterparties are carried at cost, which approximates fair value. To the extent the Company receives collateral other than cash from its counterparties such assets are not included in the Company’s balance sheet.  Notwithstanding the foregoing, if the Company either rehypothecates such assets or pledges the assets as collateral pursuant to a repurchase agreement, the cash received and the corresponding liability is reflected on the balance sheet. </div>falsefalsefalsenonnum:textBlockItemTypenaDisclosure of accounting policy for due from and due to counterparties. Due from counterparties represents cash posted with counterparties and due to counterparties represents cash posted with the entity by its counterparties as collateral under derivative agreements.No definition available.false0Due from counterparties/Due to counterparties10false 2us-gaap_DerivativesPolicyTextBlockus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00<div style="font-size:10.0pt;font-family:Times New Roman;"> Derivatives and hedging activities   Subject to maintaining its qualification as a REIT for U.S. federal income tax purposes, the Company utilizes derivative financial instruments, including interest rate swaps, swaptions, U.S. Treasuries, to-be-announced securities (“TBAs”) and Agency Interest-Only Strips to hedge the interest rate risk associated with its portfolio and related borrowings. Derivatives are used for hedging purposes rather than speculation. The Company determines the fair value of its derivative positions and obtains quotations from a third party to facilitate the process of determining these fair values. If the Company’s hedging activities do not achieve the desired results, reported earnings may be adversely affected.   GAAP requires an entity to recognize all derivatives as either assets or liabilities and to measure those instruments at fair value. The accounting for changes in the fair value of derivatives depends on the intended use of the derivative, whether the Company has elected to designate a derivative in a hedging relationship and apply hedge accounting and whether the hedging relationship has satisfied the criteria necessary to apply hedge accounting. Derivatives are classified as either hedges of the fair value of a recognized asset or liability or of an unrecognized firm commitment (fair value hedge) or hedges of a forecasted transaction or the variability of cash flows to be received or paid related to a recognized asset or liability (cash flow hedge).  Fair value adjustments are recorded in earnings immediately, if the Company does not elect hedge accounting for a derivative instrument.   The Company elected not to apply hedge accounting for its derivative instruments and records the change in fair value and net interest rate swap payments (including accrued amounts) related to interest rate swaps in Gain (loss) on derivative instruments, net in its Statement of Operations.   The Company also invests in Agency Interest-Only Strips, Agency Inverse Interest-Only Strips, swaptions and TBAs. The Company evaluates the terms and conditions of its holdings of Agency Interest-Only Strips, Agency Inverse Interest-Only Strips, swaptions and TBAs to determine if these instruments have the characteristics of an investment or should be considered a derivative under GAAP.  Accordingly, Agency Interest-Only Strips, Agency Inverse Interest-Only Strips, swaptions and TBAs having the characteristics of derivatives are accounted for at fair value with such changes recognized in Gain (loss) on derivative instruments, net in its Statement of Operations, along with any interest earned (including accrued amounts). The carrying value of these Agency Interest-Only Strips, Agency Inverse Interest-Only Strips, swaptions and TBAs is included in Residential mortgage-backed securities on the Balance Sheet.   The Company evaluates all of its financial instruments to determine if such instruments are derivatives or contain features that qualify as embedded derivatives. See “Warrants” below. Derivative instruments are recorded at fair value and are re-valued at each reporting date, with changes in the fair value together with interest earned (including accrued amounts) reported in the Gain (loss) on derivatives, net  in the Statements of Operations. </div>falsefalsefalsenonnum:textBlockItemTypenaDisclosure of accounting policy for its derivative instruments and hedging activities.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 08 -Paragraph n -Article 4 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6367646&loc=d3e18780-107790 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=7476318&loc=d3e41620-113959 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5579245-113959 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5579240-113959 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=7476318&loc=d3e41638-113959 Reference 7: 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.(n)) -URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690 Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 44 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 9: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=7476318&loc=d3e41675-113959 Reference 10: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Interpretation (FIN) -Number 39 -Paragraph 10 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false0Derivatives and hedging activities11false 2us-gaap_RepurchaseAgreementsCollateralPolicyus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00<div style="font-size:10.0pt;font-family:Times New Roman;"> Repurchase agreements   Mortgage-backed securities sold under repurchase agreements are treated as collateralized financing transactions, unless they meet sales treatment. Securities financed through a repurchase agreement remain on the Company’s Balance Sheet as an asset and cash received from the lender is recorded in the Company’s Balance Sheet as a liability, unless they are accounted for as linked transactions, described below. Interest paid in accordance with repurchase agreements is recorded as interest expense, unless they are accounted for as linked transactions, described below.  The Company reflects all proceeds from repurchase agreement borrowings and repayment of repurchase agreement borrowings which are not linked transactions, including transactions pertaining to collateral received with respect with certain swap transactions, on a gross basis on the Statement of Cash Flows. </div>falsefalsefalsenonnum:textBlockItemTypenaDisclosure of accounting policy with regard to collateral required and collateral rights on securities sold under agreements to repurchase.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 30 -Section 50 -Paragraph 1A -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=7523297&loc=SL6224234-111729 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 140 -Paragraph 17 -Subparagraph a(1) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number FAS140-4/FIN46(R)-8 -Paragraph B6 -Subparagraph a -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false0Repurchase agreements12false 2wmc_LinkedTransactionsPolicyTextBlockwmc_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00<div style="font-size:10.0pt;font-family:Times New Roman;"> Linked Transactions   In instances where the Company finances securities through repurchase agreements with the same counterparty from which the securities were purchased, the Company accounts for the purchase commitment and repurchase agreement on a net basis and records a forward commitment to purchase securities as a derivative instrument if the transaction does not comply with the criteria for gross presentation.  Such forward commitments are recorded at fair value with subsequent changes in fair value recognized in Gain on linked transactions, net on its Statement of Operations. If the transaction complies with the criteria for gross presentation, the Company records the assets and the related financing on a gross basis in its Balance Sheet and the corresponding interest income and interest expense in its Statement of Operations. </div>falsefalsefalsenonnum:textBlockItemTypenaDisclosure of accounting policy for linked transactions.No definition available.false0Linked Transactions13false 2us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicyus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00<div style="font-size:10.0pt;font-family:Times New Roman;"> Share-based compensation   The Company accounts for share-based compensation to its independent directors, to its employees, to its Manager and to employees of its Manager and its affiliates using the fair value based methodology prescribed by GAAP.  Compensation cost related to restricted common stock issued to the Company’s independent directors, including any such restricted stock which is subject to a deferred compensation program, and employees of the Company is measured at its fair value at the grant date, and amortized into expense over the service period on a straight-line basis. Compensation cost related to restricted common stock issued to the Manager and to employees of the Manager and its affiliates is initially measured at fair value at the grant date, and amortized into expense over the vesting period on a straight-line basis and re-measured on subsequent dates to the extent the awards are unvested. </div>falsefalsefalsenonnum:textBlockItemTypenaDisclosure of accounting policy for stock option and stock incentive plans. This disclosure may include (1) the types of stock option or incentive plans sponsored by the entity (2) the groups that participate in (or are covered by) each plan (3) significant plan provisions and (4) how stock compensation is measured, and the methodologies and significant assumptions used to determine that measurement.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6367646&loc=d3e18780-107790 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph a -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b),(f) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -URI http://asc.fasb.org/subtopic&trid=2228939 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Emerging Issues Task Force (EITF) -Number 06-11 -Paragraph 7 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false0Share-based compensation14false 2wmc_WarrantsPolicyTextBlockwmc_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00<div style="font-size:10.0pt;font-family:Times New Roman;"> Warrants   The Company evaluates all of its financial instruments to determine if such instruments are derivatives or contain features that qualify as embedded derivatives. For derivative financial instruments that are accounted for as liabilities, the derivative instrument is initially recorded at its fair value and is then re-valued at each reporting date, with changes in the fair value reported in the statements of operations.  Financial instruments without the features of liabilities are recorded as a component of equity.  For the Company’s warrants, the Company uses a variation of the adjusted Black-Scholes option valuation model to record the financial instruments at their relative fair values at issuance. The warrants issued with the Company’s common stock in the private placement to certain accredited institutional investors on May 15, 2012, were evaluated by the Company and were recorded at their relative fair value as a component of equity at the date of issuance. </div>falsefalsefalsenonnum:textBlockItemTypenaDescribes the entity's accounting policy for warrants.No definition available.false0Warrants15false 2us-gaap_IncomeTaxPolicyTextBlockus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00<div style="font-size:10.0pt;font-family:Times New Roman;"> Income taxes   The Company intends to elect and qualify to be taxed as a REIT commencing with its taxable year ended December 31, 2012. Accordingly, the Company will generally not be subject to corporate U.S. federal or state income tax to the extent that the Company makes qualifying distributions to stockholders, and provided that the Company satisfies, on a continuing basis, through actual investment and operating results, the REIT requirements including certain asset, income, distribution and stock ownership tests. If the Company fails to qualify as a REIT, and does not qualify for certain statutory relief provisions, the Company will be subject to U.S. federal, state and local income taxes and may be precluded from qualifying as a REIT for the subsequent four taxable years following the year in which the Company lost its REIT qualification. Accordingly, the failure to qualify as a REIT could have a material adverse impact on the Company’s results of operations and amounts available for distribution to stockholders.   The dividends paid deduction for qualifying dividends paid to stockholders is computed using the Company’s taxable income as opposed to net income reported on the financial statements. Taxable income, generally, will differ from net income reported on the financial statements because the determination of taxable income is based on tax provisions and not GAAP.   The Company may create and elect to treat certain subsidiaries as Taxable REIT Subsidiaries (“TRS”). In general, a TRS may hold assets and engage in activities that the Company cannot hold or engage in directly and generally may engage in any real estate or non-real estate-related business. A TRS is subject to U.S. federal, state and local corporate income taxes, and its value may not exceed 25% of the value of the Company. While a TRS will generate net income, a TRS can declare dividends to the Company, which will be included in the Company’s taxable income and necessitate a distribution to its stockholders. Conversely, if the Company retains earnings at the TRS level, no distribution is required and it can increase book equity of the consolidated entity.  As of June 30, 2013, the Company did not have a TRS, or any other subsidiary.   The Company evaluates uncertain tax positions, if any, and classifies interest and penalties, if any, related to unrecognized tax benefits as a component of the provision for income taxes. </div>falsefalsefalsenonnum:textBlockItemTypenaDisclosure of accounting policy for income taxes, which may include its accounting policies for recognizing and measuring deferred tax assets and liabilities and related valuation allowances, recognizing investment tax credits, operating loss carryforwards, tax credit carryforwards, and other carryforwards, methodologies for determining its effective income tax rate and the characterization of interest and penalties in the financial statements.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 4 -Paragraph 11 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Interpretation (FIN) -Number 48 -Paragraph 20 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6367646&loc=d3e18780-107790 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 45 -Paragraph 25 -URI http://asc.fasb.org/extlink&oid=21917399&loc=d3e32247-109318 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 19 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32840-109319 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 30 -URI http://asc.fasb.org/subtopic&trid=2144749 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 954 -SubTopic 740 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6491622&loc=d3e9504-115650 Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -URI http://asc.fasb.org/subtopic&trid=2144681 Reference 9: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 17 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32809-109319 Reference 10: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=21917399&loc=d3e32280-109318 Reference 11: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 6-34, 43, 47, 49 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false0Income taxes16false 2wmc_OfferingCostsPolicyTextBlockwmc_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00<div style="font-size:10.0pt;font-family:Times New Roman;"> Offering costs   Offering costs borne by the Company in connection with the IPO and concurrent private placements completed on May 15, 2012 as well as its follow-on public stock offering completed on October 3, 2012 are reflected as a reduction of additional paid-in-capital. </div>falsefalsefalsenonnum:textBlockItemTypenaRepresents the accounting policies related to offering costs.No definition available.false0Offering costs17false 2us-gaap_EarningsPerSharePolicyTextBlockus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00<div style="font-size:10.0pt;font-family:Times New Roman;"> Earnings per share   GAAP requires use of the two-class method of computing earnings per share for all periods presented for each class of common stock and participating securities as if all earnings for the period had been distributed.  Under the two-class method, during periods of net income, the net income is first reduced for dividends declared on all classes of securities to arrive at undistributed earnings.  During periods of net losses, the net loss is reduced for dividends declared on participating securities only if the security has the right to participate in the earnings of the entity and an objectively determinable contractual obligation to share in net losses of the entity.   The remaining earnings are allocated to common stockholders and participating securities, to the extent that each security shares in earnings, as if all of the earnings for the period had been distributed.  Each total is then divided by the applicable number of shares to arrive at basic earnings per share.  For the diluted earnings, the denominator includes all outstanding common shares and all potential common shares assumed issued if they are dilutive.  The numerator is adjusted for any changes in income or loss that would result from the assumed conversion of these potential common shares. </div>falsefalsefalsenonnum:textBlockItemTypenaDisclosure of accounting policy for computing basic and diluted earnings or loss per share for each class of common stock and participating security. Addresses all significant policy factors, including any antidilutive items that have been excluded from the computation and takes into account stock dividends, splits and reverse splits that occur after the balance sheet date of the latest reporting period but before the issuance of the financial statements.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6367646&loc=d3e18780-107790 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -URI http://asc.fasb.org/subtopic&trid=2144384 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 128 -Paragraph 40 -Subparagraph a -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3630-109257 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 128 -Paragraph 6, 8-16, 60 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false0Earnings per share18false 2us-gaap_ComprehensiveIncomePolicyPolicyTextBlockus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00<div style="font-size:10.0pt;font-family:Times New Roman;"> Comprehensive Income (Loss)   The Company has none of the components of comprehensive income (loss) and therefore comprehensive income (loss) is not presented. </div>falsefalsefalsenonnum:textBlockItemTypenaDisclosure of accounting policy for comprehensive income.No definition available.false0Comprehensive Income (Loss)19false 2wmc_AccountingStandardsApplicableToEmergingGrowthCompaniesPolicyTextBlockwmc_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00<div style="font-size:10.0pt;font-family:Times New Roman;"> Accounting standards applicable to emerging growth companies   The JOBS Act contains provisions that relax certain requirements for “emerging growth companies”, which includes the Company. For as long as the Company is an emerging growth company, which may be up to five full fiscal years, unlike other public companies, the Company will not be required to: (i) comply with any new or revised financial accounting standards applicable to public companies until such standards are also applicable to private companies under Section 102(b)(1) of the JOBS Act; (ii) provide an auditor’s attestation report on management’s assessment of the effectiveness of the Company’s system of internal control over financial reporting pursuant to Section 404 of the Sarbanes-Oxley Act; (iii) comply with any new requirements adopted by the PCAOB requiring mandatory audit firm rotation or a supplement to the auditor’s report in which the auditor would be required to provide additional information about the audit and the financial statements of the issuer; or (iv) comply with any new audit rules adopted by the PCAOB after April 5, 2012, unless the SEC determines otherwise.   As noted above, under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards that have different effective dates for public and private companies until such time as those standards apply to private companies. The Company intends to take advantage of such extended transition period. Since the Company will not be required to comply with new or revised accounting standards on the relevant dates on which adoption of such standards is required for other public companies, its financial statements may not be comparable to the financial statements of companies that comply with public company effective dates. If the Company were to elect to comply with these public company effective dates, such election would be irrevocable pursuant to Section 107 of the JOBS Act. </div>falsefalsefalsenonnum:textBlockItemTypenaDisclosure of accounting policy for accounting standards applicable to emerging growth companies.No definition available.false0Accounting standards applicable to emerging growth companies20false 2us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlockus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00<div style="font-size:10.0pt;font-family:Times New Roman;"> Recent accounting pronouncements   Accounting Standards Adoptedin 2013   In December 2011, the FASB issued guidance requiring additional disclosure information about offsetting and related arrangements.  Further in December 2012, the FASB proposed an update intended to address implementation of the December 2011 guidance. In January 2013, the FASB issued guidance to limit the scope of the new balance sheet and offsetting disclosure requirements of prior guidance related  to certain derivatives (including bifurcated embedded derivatives,) repurchase agreements and reverse repurchase agreements, and securities borrowing and securities lending transactions. Entities will be required to disclose both gross information and net information about both instruments and transactions eligible for offset in the balance sheet as well as instruments and transactions subject to an agreement similar to a master netting arrangement. This scope would include derivatives, sale and repurchase agreements and reverse sale and repurchase agreements and securities lending arrangements. The objective of this disclosure is to facilitate comparison between those entities that prepare their financial statements on the basis of GAAP and those entities that prepare their financial statements on the basis of International Financial Reporting Standards. The guidance is effective for periods beginning on or after January 1, 2013 and interim periods within those annual periods. While this guidance did result in certain additional disclosures, it did not have a material impact on the Company’s financial statements. </div>falsefalsefalsenonnum:textBlockItemTypenaDisclosure of the adoption of new accounting pronouncements that may impact the entity's financial reporting.No definition available.false0Recent accounting pronouncementsfalseSummary of Significant Accounting Policies (Policies)UnKnownUnKnownUnKnownUnKnowntruefalsefalseSheethttp://www.westernassetmcc.com/role/DisclosureSummaryOfSignificantAccountingPoliciesPolicies120