Debt MIF Warehousing Agreement (Details) $ in Thousands	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Debt Instrument [Line Items]
Maximum Borrowing Availability under all Credit Lines	$ 175,000	$ 225,000
Notes payable bank - financial service operations	104,026	$ 153,168
Warehousing Agreement - Second Amendment to Second Amended and Restated [Member]
Debt Instrument [Line Items]
M/I Financial Maximum Borrowing Capacity	125,000
M/I Financial Temporary Increase Maximum Borrowing Capacity	$ 160,000
LIBOR basis points	200.0
Repurchase Agreement - First Amendment to Second Amended and Restated [Member]
Debt Instrument [Line Items]
M/I Financial Maximum Borrowing Capacity	$ 50,000
M/I Financial Temporary Increase Maximum Borrowing Capacity	$ 65,000
Minimum [Member] | Repurchase Agreement - First Amendment to Second Amended and Restated [Member]
Debt Instrument [Line Items]
LIBOR basis points	200
Maximum [Member] | Repurchase Agreement - First Amendment to Second Amended and Restated [Member]
Debt Instrument [Line Items]
LIBOR basis points	225