Debt	6 Months Ended
Jun. 30, 2018
Debt Disclosure [Abstract]
Debt Disclosure [Text Block]	Debt Notes Payable - Homebuilding The Credit Facility provides an aggregate commitment amount of $500 million, including a $125 million sub-facility for letters of credit. During the second quarter of 2018, the Company exercised an accordion feature provided for within the Credit Facility, which increased the total revolving commitment under the Credit Facility from $475 million to $500 million by obtaining a commitment from an additional lender of $25 million. The Credit Facility expires on July 18, 2021. Interest on amounts borrowed under the Credit Facility was payable at a rate which is adjusted daily and is equal to the sum of the one-month LIBOR rate plus a margin of 250 basis points. The margin is subject to adjustment in subsequent quarterly periods based on the Company’s leverage ratio. The Credit Facility also contains certain financial covenants. At June 30, 2018, the Company was in compliance with all financial covenants of the Credit Facility. The available amount under the Credit Facility is computed in accordance with a borrowing base, which is calculated by applying various advance rates for different categories of inventory, and totaled $622.9 million of availability for additional senior debt at June 30, 2018. As a result, the full $500 million commitment amount of the Credit Facility was available, less any borrowings and letters of credit outstanding. At June 30, 2018, there were $181.8 million of borrowings outstanding and $49.6 million of letters of credit outstanding, leaving net remaining borrowing availability of $268.6 million. The Company’s obligations under the Credit Facility are guaranteed by all of the Company’s subsidiaries, with the exception of subsidiaries that are primarily engaged in the business of mortgage financing, title insurance or similar financial businesses relating to the homebuilding and home sales business, certain subsidiaries that are not 100%-owned by the Company or another subsidiary, and other subsidiaries designated by the Company as Unrestricted Subsidiaries (as defined in Note 12 to our financial statements), subject to limitations on the aggregate amount invested in such Unrestricted Subsidiaries in accordance with the terms of the Credit Facility and the indentures for the Company’s $250.0 million aggregate principal amount of 5.625% Senior Notes due 2025 (the “2025 Senior Notes”) and the Company’s $300.0 million aggregate principal amount of 6.75% Senior Notes due 2021 (the “2021 Senior Notes”). The guarantors for the Credit Facility (the “Guarantor Subsidiaries”) are the same subsidiaries that guarantee the 2025 Senior Notes and the 2021 Senior Notes. The Company’s obligations under the Credit Facility are general, unsecured senior obligations of the Company and the Guarantor Subsidiaries and rank equally in right of payment with all our and the Guarantor Subsidiaries’ existing and future unsecured senior indebtedness. Our obligations under the Credit Facility are effectively subordinated to our and the Guarantor Subsidiaries’ existing and future secured indebtedness with respect to any assets comprising security or collateral for such indebtedness. As of June 30, 2018, the Company was a party to a secured credit facility agreement for the issuance of letters of credit (the “Letter of Credit Facility”), with a maturity date of September 30, 2018 which allows for the issuance of letters of credit up to a total of $1.0 million. At June 30, 2018 and December 31, 2017, there was $0.2 million and $0.6 million, respectively, of outstanding letters of credit in aggregate under the Letter of Credit Facility, which were collateralized with $0.2 million and $0.6 million, respectively, of the Company’s cash. In connection with the acquisition of Pinnacle Homes in March 2018, the Company assumed the obligation for $6.6 million of outstanding letters of credit under a separate facility, which was collateralized with $6.6 million of restricted cash. During the second quarter of 2018, the Company terminated this separate letter of credit facility and the outstanding letters of credit under the facility were transferred to the Credit Facility, resulting in the release of approximately $6.6 million of restricted cash which collateralized the separate facility. Notes Payable — Financial Services The MIF Mortgage Warehousing Agreement is used to finance eligible residential mortgage loans originated by M/I Financial. The MIF Mortgage Warehousing Agreement provides for a maximum borrowing availability of $125 million. In June 2018, the Company entered into an amendment to the MIF Mortgage Warehousing Agreement, which, among other things, extended the expiration date to June 21, 2019 and adjusted the interest rate to a per annum rate equal to the greater of (1) the floating LIBOR rate plus a spread of 200 basis points and (2) 2.75%. The spread over floating LIBOR had previously been 237.5 basis points. The amendment also allows the maximum borrowing availability to be increased to $160 million during certain periods of expected increases in the volume of mortgage originations, specifically from September 25, 2018 to October 15, 2018 and from November 15, 2018 to February 4, 2019. The MIF Mortgage Warehousing Agreement also contains certain financial covenants. At June 30, 2018, M/I Financial was in compliance with all financial covenants of the MIF Mortgage Warehousing Agreement. The MIF Mortgage Repurchase Facility is used to finance eligible residential mortgage loans originated by M/I Financial. The MIF Repurchase Facility provides for a mortgage repurchase facility with a maximum borrowing availability of $35 million which increased to $50 million from November 15, 2017 through February 1, 2018 (a period during which we typically experience higher mortgage origination volume). The MIF Mortgage Repurchase Facility expires on October 29, 2018. M/I Financial pays interest on each advance under the MIF Mortgage Repurchase Facility at a per annum rate equal to the floating LIBOR rate plus 250 or 275 basis points depending on the loan type. The MIF Mortgage Repurchase Facility also contains certain financial covenants. At June 30, 2018, M/I Financial was in compliance with all financial covenants of the MIF Mortgage Repurchase Facility. At June 30, 2018 and December 31, 2017, M/I Financial’s total combined maximum borrowing availability under the two credit facilities was $160.0 million and $200.0 million, respectively. At June 30, 2018 and December 31, 2017, M/I Financial had $93.2 million and $168.2 million outstanding on a combined basis under its credit facilities, respectively. Senior Notes As of both June 30, 2018 and December 31, 2017, we had $250.0 million of our 2025 Senior Notes outstanding. The 2025 Senior Notes bear interest at a rate of 5.625% per year, payable semiannually in arrears on February 1 and August 1 of each year (commencing on February 1, 2018), and mature on August 1, 2025. We may redeem all or any portion of the 2025 Senior Notes on or after August 1, 2020 at a stated redemption price, together with accrued and unpaid interest thereon. The redemption price will initially be 104.219% of the principal amount outstanding, but will decline to 102.813% of the principal amount outstanding if redeemed during the 12-month period beginning on August 1, 2021, will further decline to 101.406% of the principal amount outstanding if redeemed during the 12-month period beginning on August 1, 2022 and will further decline to 100.000% of the principal amount outstanding if redeemed on or after August 1, 2023, but prior to maturity. As of both June 30, 2018 and December 31, 2017, we had $300.0 million of our 2021 Senior Notes outstanding. The 2021 Senior Notes bear interest at a rate of 6.75% per year, payable semiannually in arrears on January 15 and July 15 of each year, and mature on January 15, 2021. As of January 15, 2018, we may redeem all or any portion of the 2021 Senior Notes at 103.375% of the principal amount outstanding. This rate declines to 101.688% of the principal amount outstanding if redeemed during the 12-month period beginning on January 15, 2019, and will further decline to 100.000% of the principal amount outstanding if redeemed on or after January 15, 2020, but prior to maturity. The 2025 Senior Notes and the 2021 Senior Notes contain certain covenants, as more fully described and defined in the indenture governing the 2025 Senior Notes and the indenture governing the 2021 Senior Notes, which limit the ability of the Company and the restricted subsidiaries to, among other things: incur additional indebtedness; make certain payments, including dividends, or repurchase any shares, in an aggregate amount exceeding our “restricted payments basket”; make certain investments; and create or incur certain liens, consolidate or merge with or into other companies, or liquidate or sell or transfer all or substantially all of our assets. These covenants are subject to a number of exceptions and qualifications as described in the indenture governing the 2025 Senior Notes and the indenture governing the 2021 Senior Notes. As of June 30, 2018, the Company was in compliance with all terms, conditions, and covenants under the indentures. The 2025 Senior Notes and the 2021 Senior Notes are fully and unconditionally guaranteed jointly and severally on a senior unsecured basis by the Guarantor Subsidiaries. The 2025 Senior Notes and the 2021 Senior Notes are general, unsecured senior obligations of the Company and the Guarantor Subsidiaries and rank equally in right of payment with all our and the Guarantor Subsidiaries’ existing and future unsecured senior indebtedness. The 2025 Senior Notes and the 2021 Senior Notes are effectively subordinated to our and the Guarantor Subsidiaries’ existing and future secured indebtedness with respect to any assets comprising security or collateral for such indebtedness. The indenture governing our 2025 Senior Notes and the indenture governing the 2021 Senior Notes limits our ability to pay dividends on, and repurchase, our common shares and any of our preferred shares then outstanding to the amount of the positive balance in our “restricted payments basket,” as defined in the indentures. In each case, the “restricted payments basket” is equal to $125.0 million plus (1) 50% of our aggregate consolidated net income (or minus 100% of our aggregate consolidated net loss) from October 1, 2015, excluding income or loss from Unrestricted Subsidiaries, plus (2) 100% of the net cash proceeds from either contributions to the common equity of the Company after December 1, 2015 or the sale of qualified equity interests after December 1, 2015, plus other items and subject to other exceptions. The restricted payments basket was $214.0 million and $176.1 million at June 30, 2018 and December 31, 2017, respectively. The determination to pay future dividends on, or make future repurchases of, our common shares will be at the discretion of our board of directors and will depend upon our results of operations, financial condition, capital requirements and compliance with debt covenants, and other factors deemed relevant by our board of directors. Convertible Senior Subordinated Notes On March 1, 2013, the Company issued $86.3 million in aggregate principal amount of 3.0% Convertible Senior Subordinated Notes due 2018 (the “2018 Convertible Senior Subordinated Notes”). The 2018 Convertible Senior Subordinated Notes were scheduled to mature on March 1, 2018 and the deadline for holders to convert the 2018 Convertible Senior Subordinated Notes was February 27, 2018. As a result of conversion elections made by holders of the 2018 Convertible Senior Subordinated Notes, (1) approximately $20.3 million in aggregate principal amount of the 2018 Convertible Senior Subordinated Notes were converted and settled through the issuance of approximately 0.629 million of our common shares (at a conversion price per common share of $32.31) and (2) the Company repaid in cash approximately $65.9 million in aggregate principal amount of the 2018 Convertible Senior Subordinated Notes at maturity. In accordance with the indenture governing the 2018 Convertible Senior Subordinated Notes, the Company paid interest on the 2018 Convertible Senior Subordinated Notes to, but excluding, March 1, 2018. On December 31, 2017, we had $86.3 million of our 2018 Convertible Senior Subordinated Notes outstanding. Notes Payable - Other The Company had other borrowings, which are reported in Notes Payable - Other in our Unaudited Condensed Consolidated Balance Sheets, totaling $9.4 million and $10.6 million as of June 30, 2018 and December 31, 2017, respectively. The balance is made up of notes payable acquired in the normal course of business.

Debt

Notes Payable - Homebuilding

The Credit Facility provides an aggregate commitment amount of $500 million, including a $125 million sub-facility for letters of credit. During the second quarter of 2018, the Company exercised an accordion feature provided for within the Credit Facility, which increased the total revolving commitment under the Credit Facility from $475 million to $500 million by obtaining a commitment from an additional lender of $25 million. The Credit Facility expires on July 18, 2021. Interest on amounts borrowed under the Credit Facility was payable at a rate which is adjusted daily and is equal to the sum of the one-month LIBOR rate plus a margin of 250 basis points. The margin is subject to adjustment in subsequent quarterly periods based on the Company’s leverage ratio. The Credit Facility also contains certain financial covenants. At June 30, 2018, the Company was in compliance with all financial covenants of the Credit Facility.

The available amount under the Credit Facility is computed in accordance with a borrowing base, which is calculated by applying various advance rates for different categories of inventory, and totaled $622.9 million of availability for additional senior debt at June 30, 2018. As a result, the full $500 million commitment amount of the Credit Facility was available, less any borrowings and letters of credit outstanding. At June 30, 2018, there were $181.8 million of borrowings outstanding and $49.6 million of letters of credit outstanding, leaving net remaining borrowing availability of $268.6 million.

The Company’s obligations under the Credit Facility are guaranteed by all of the Company’s subsidiaries, with the exception of subsidiaries that are primarily engaged in the business of mortgage financing, title insurance or similar financial businesses relating to the homebuilding and home sales business, certain subsidiaries that are not 100%-owned by the Company or another subsidiary, and other subsidiaries designated by the Company as Unrestricted Subsidiaries (as defined in Note 12 to our financial statements), subject to limitations on the aggregate amount invested in such Unrestricted Subsidiaries in accordance with the terms of the Credit Facility and the indentures for the Company’s $250.0 million aggregate principal amount of 5.625% Senior Notes due 2025 (the “2025 Senior Notes”) and the Company’s $300.0 million aggregate principal amount of 6.75% Senior Notes due 2021 (the “2021 Senior Notes”). The guarantors for the Credit Facility (the “Guarantor Subsidiaries”) are the same subsidiaries that guarantee the 2025 Senior Notes and the 2021 Senior Notes.

The Company’s obligations under the Credit Facility are general, unsecured senior obligations of the Company and the Guarantor Subsidiaries and rank equally in right of payment with all our and the Guarantor Subsidiaries’ existing and future unsecured senior indebtedness. Our obligations under the Credit Facility are effectively subordinated to our and the Guarantor Subsidiaries’ existing and future secured indebtedness with respect to any assets comprising security or collateral for such indebtedness.

As of June 30, 2018, the Company was a party to a secured credit facility agreement for the issuance of letters of credit (the “Letter of Credit Facility”), with a maturity date of September 30, 2018 which allows for the issuance of letters of credit up to a total of $1.0 million. At June 30, 2018 and December 31, 2017, there was $0.2 million and $0.6 million, respectively, of outstanding letters of credit in aggregate under the Letter of Credit Facility, which were collateralized with $0.2 million and $0.6 million, respectively, of the Company’s cash. In connection with the acquisition of Pinnacle Homes in March 2018, the Company assumed the obligation for $6.6 million of outstanding letters of credit under a separate facility, which was collateralized with $6.6 million of restricted cash. During the second quarter of 2018, the Company terminated this separate letter of credit facility and the outstanding letters of credit under the facility were transferred to the Credit Facility, resulting in the release of approximately $6.6 million of restricted cash which collateralized the separate facility.

Notes Payable — Financial Services

The MIF Mortgage Warehousing Agreement is used to finance eligible residential mortgage loans originated by M/I Financial. The MIF Mortgage Warehousing Agreement provides for a maximum borrowing availability of $125 million. In June 2018, the Company entered into an amendment to the MIF Mortgage Warehousing Agreement, which, among other things, extended the expiration date to June 21, 2019 and adjusted the interest rate to a per annum rate equal to the greater of (1) the floating LIBOR rate plus a spread of 200 basis points and (2) 2.75%. The spread over floating LIBOR had previously been 237.5 basis points. The amendment also allows the maximum borrowing availability to be increased to $160 million during certain periods of expected increases in the volume of mortgage originations, specifically from September 25, 2018 to October 15, 2018 and from November 15, 2018 to February 4, 2019. The MIF Mortgage Warehousing Agreement also contains certain financial covenants. At June 30, 2018, M/I Financial was in compliance with all financial covenants of the MIF Mortgage Warehousing Agreement.

The MIF Mortgage Repurchase Facility is used to finance eligible residential mortgage loans originated by M/I Financial. The MIF Repurchase Facility provides for a mortgage repurchase facility with a maximum borrowing availability of $35 million which increased to $50 million from November 15, 2017 through February 1, 2018 (a period during which we typically experience higher mortgage origination volume). The MIF Mortgage Repurchase Facility expires on October 29, 2018. M/I Financial pays interest on each advance under the MIF Mortgage Repurchase Facility at a per annum rate equal to the floating LIBOR rate plus 250 or 275 basis points depending on the loan type. The MIF Mortgage Repurchase Facility also contains certain financial covenants. At June 30, 2018, M/I Financial was in compliance with all financial covenants of the MIF Mortgage Repurchase Facility.

At June 30, 2018 and December 31, 2017, M/I Financial’s total combined maximum borrowing availability under the two credit facilities was $160.0 million and $200.0 million, respectively. At June 30, 2018 and December 31, 2017, M/I Financial had $93.2 million and $168.2 million outstanding on a combined basis under its credit facilities, respectively.

Senior Notes

As of both June 30, 2018 and December 31, 2017, we had $250.0 million of our 2025 Senior Notes outstanding. The 2025 Senior Notes bear interest at a rate of 5.625% per year, payable semiannually in arrears on February 1 and August 1 of each year (commencing on February 1, 2018), and mature on August 1, 2025. We may redeem all or any portion of the 2025 Senior Notes on or after August 1, 2020 at a stated redemption price, together with accrued and unpaid interest thereon. The redemption price will initially be 104.219% of the principal amount outstanding, but will decline to 102.813% of the principal amount outstanding if redeemed during the 12-month period beginning on August 1, 2021, will further decline to 101.406% of the principal amount outstanding if redeemed during the 12-month period beginning on August 1, 2022 and will further decline to 100.000% of the principal amount outstanding if redeemed on or after August 1, 2023, but prior to maturity.

As of both June 30, 2018 and December 31, 2017, we had $300.0 million of our 2021 Senior Notes outstanding. The 2021 Senior Notes bear interest at a rate of 6.75% per year, payable semiannually in arrears on January 15 and July 15 of each year, and mature on January 15, 2021. As of January 15, 2018, we may redeem all or any portion of the 2021 Senior Notes at 103.375% of the principal amount outstanding. This rate declines to 101.688% of the principal amount outstanding if redeemed during the 12-month period beginning on January 15, 2019, and will further decline to 100.000% of the principal amount outstanding if redeemed on or after January 15, 2020, but prior to maturity.

The 2025 Senior Notes and the 2021 Senior Notes contain certain covenants, as more fully described and defined in the indenture governing the 2025 Senior Notes and the indenture governing the 2021 Senior Notes, which limit the ability of the Company and the restricted subsidiaries to, among other things: incur additional indebtedness; make certain payments, including dividends, or repurchase any shares, in an aggregate amount exceeding our “restricted payments basket”; make certain investments; and create or incur certain liens, consolidate or merge with or into other companies, or liquidate or sell or transfer all or substantially all of our assets. These covenants are subject to a number of exceptions and qualifications as described in the indenture governing the 2025 Senior Notes and the indenture governing the 2021 Senior Notes. As of June 30, 2018, the Company was in compliance with all terms, conditions, and covenants under the indentures.

The 2025 Senior Notes and the 2021 Senior Notes are fully and unconditionally guaranteed jointly and severally on a senior unsecured basis by the Guarantor Subsidiaries. The 2025 Senior Notes and the 2021 Senior Notes are general, unsecured senior obligations of the Company and the Guarantor Subsidiaries and rank equally in right of payment with all our and the Guarantor Subsidiaries’ existing and future unsecured senior indebtedness. The 2025 Senior Notes and the 2021 Senior Notes are effectively subordinated to our and the Guarantor Subsidiaries’ existing and future secured indebtedness with respect to any assets comprising security or collateral for such indebtedness.

The indenture governing our 2025 Senior Notes and the indenture governing the 2021 Senior Notes limits our ability to pay dividends on, and repurchase, our common shares and any of our preferred shares then outstanding to the amount of the positive balance in our “restricted payments basket,” as defined in the indentures. In each case, the “restricted payments basket” is equal to $125.0 million plus (1) 50% of our aggregate consolidated net income (or minus 100% of our aggregate consolidated net loss) from October 1, 2015, excluding income or loss from Unrestricted Subsidiaries, plus (2) 100% of the net cash proceeds from either contributions to the common equity of the Company after December 1, 2015 or the sale of qualified equity interests after December 1, 2015, plus other items and subject to other exceptions. The restricted payments basket was $214.0 million and $176.1 million at June 30, 2018 and December 31, 2017, respectively. The determination to pay future dividends on, or make future repurchases of, our common shares will be at the discretion of our board of directors and will depend upon our results of operations, financial condition, capital requirements and compliance with debt covenants, and other factors deemed relevant by our board of directors.

Convertible Senior Subordinated Notes

On March 1, 2013, the Company issued $86.3 million in aggregate principal amount of 3.0% Convertible Senior Subordinated Notes due 2018 (the “2018 Convertible Senior Subordinated Notes”). The 2018 Convertible Senior Subordinated Notes were scheduled to mature on March 1, 2018 and the deadline for holders to convert the 2018 Convertible Senior Subordinated Notes was February 27, 2018. As a result of conversion elections made by holders of the 2018 Convertible Senior Subordinated Notes, (1) approximately $20.3 million in aggregate principal amount of the 2018 Convertible Senior Subordinated Notes were converted and settled through the issuance of approximately 0.629 million of our common shares (at a conversion price per common share of $32.31) and (2) the Company repaid in cash approximately $65.9 million in aggregate principal amount of the 2018 Convertible Senior Subordinated Notes at maturity. In accordance with the indenture governing the 2018 Convertible Senior Subordinated Notes, the Company paid interest on the 2018 Convertible Senior Subordinated Notes to, but excluding, March 1, 2018. On December 31, 2017, we had $86.3 million of our 2018 Convertible Senior Subordinated Notes outstanding.

Notes Payable - Other

The Company had other borrowings, which are reported in Notes Payable - Other in our Unaudited Condensed Consolidated Balance Sheets, totaling $9.4 million and $10.6 million as of June 30, 2018 and December 31, 2017, respectively. The balance is made up of notes payable acquired in the normal course of business.