Fair Value Measurements Fair Value of Financial Instrument Assumptions (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Fair Value of Financial Instrument Assumptions [Line Items]
Letters of Credit Potential Commitments, Amount	$ 37,676	$ 42,503
First Amendment to New Unsecured Credit Facility [Member]
Fair Value of Financial Instrument Assumptions [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	400,000
Warehousing Agreement - Second Amended and Restated [Member]
Fair Value of Financial Instrument Assumptions [Line Items]
M/I Financial Maximum Borrowing Capacity	125,000
Amendment No. 1 to Amended and Restated Repurchase Agreement [Member]
Fair Value of Financial Instrument Assumptions [Line Items]
M/I Financial Maximum Borrowing Capacity	$ 15,000