Debt MIF Warehousing Agreement (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Line of Credit Facility [Line Items]
Line of Credit Facility, Expiration Date	Jul. 18, 2021
Maximum Borrowing Availability under all Credit Lines	$ 225,000	$ 225,000
Notes payable bank - financial services operations	$ 136,904	$ 153,168
Warehousing Agreement - Third Amendment to Second Amended and Restated [Member]
Line of Credit Facility [Line Items]
Basis Point Spread on Variable Rate	2.00%
Line of Credit Facility, Maximum Borrowing Capacity	$ 125,000
M/I Financial Temporary Increase Maximum Borrowing Capacity	$ 160,000
Line of Credit Facility, Expiration Date	Jun. 19, 2020
Repurchase Agreement -Second Amendment to Second Amended and Restated [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 65,000
Line of Credit Facility, Expiration Date	Oct. 26, 2020
Minimum [Member] | Repurchase Agreement -Second Amendment to Second Amended and Restated [Member]
Line of Credit Facility [Line Items]
Basis Point Spread on Variable Rate	1.75%
Maximum [Member] | Repurchase Agreement -Second Amendment to Second Amended and Restated [Member]
Line of Credit Facility [Line Items]
Basis Point Spread on Variable Rate	2.00%