Debt (Schedule of Lines of Credit Outstanding) (Details) - USD ($)						12 Months Ended
	Dec. 01, 2016	Aug. 31, 2016	May 03, 2016	Dec. 15, 2015	Jul. 30, 2015	Dec. 31, 2016	Dec. 31, 2015	Mar. 06, 2017	Dec. 15, 2016
Inwood National Bank | Johns Creek Carrollton Allen
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity			$ 50,000,000
Line of Credit Facility, Interest Rate at Period End						4.00%
BorrowingBaseLimitationTotalValueOfland			50.00%
BorrowingBaseLimitationTotalValueOfLotsOwned			65.00%
MaximumValueOfLandUsedWhenCalculatingBorrowingBase			65.00%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage			0.25%
Citibank, N.A. and Credit Suisse AG, CAyman Islands Branch [Member] | Unsecured Debt
Line of Credit Facility [Line Items]
Borrowings on lines of credit						$ 60,000,000	$ 30,000,000
Subsidiary of JBGL | Inwood National Bank
Line of Credit Facility [Line Items]
Borrowings on lines of credit						75,000,000	47,500,000
Subsidiary of JBGL | Inwood National Bank | Johns Creek Carrollton Allen
Line of Credit Facility [Line Items]
Borrowings on lines of credit						15,000,000	17,500,000
Line of credit, maximum borrowing capacity					$ 50,000,000
BorrowingBaseLimitationTotalValueOfland					50.00%
BorrowingBaseLimitationTotalValueOfLotsOwned					60.00%
MaximumValueOfLandUsedWhenCalculatingBorrowingBase					50.00%
Other Assets
Line of Credit Facility [Line Items]
Debt issuance cost						$ 800,000	$ 800,000
Other Assets | Inwood National Bank | Johns Creek Carrollton Allen
Line of Credit Facility [Line Items]
Debt issuance cost			$ 100,000
Other Assets | Subsidiary of JBGL | Inwood National Bank | Johns Creek Carrollton Allen
Line of Credit Facility [Line Items]
Debt issuance cost					$ 400,000
Minimum | Subsidiary of JBGL | Inwood National Bank | Johns Creek Carrollton Allen
Line of Credit Facility [Line Items]
Stated interest rate					4.00%
Maximum | Subsidiary of JBGL | Inwood National Bank | Johns Creek Carrollton Allen
Line of Credit Facility [Line Items]
Stated interest rate					18.00%
Unsecured Debt | Citibank, N.A. and Credit Suisse AG, CAyman Islands Branch [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate				1.50%
Debt Instrument, Interest Rate, Effective Percentage						3.26%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage				0.45%
Unrestricted Cash Borrowing Base Limitation				100.00%
Borrowing Base Limitation for Unrestricted Cash				$ 15,000,000
Book Value of Model Homes Borrowing Base				85.00%
Book Value of Finished Lots and Land Under Development				65.00%
Book Value of Entitled Land				50.00%
Unsecured Debt | Citibank, N.A. and Credit Suisse AG, CAyman Islands Branch [Member] | Unsecured Revolving Credit Facility
Line of Credit Facility [Line Items]
Borrowings on lines of credit				$ 40,000,000
Unsecured Debt | Flagstar Bank [Member] | Unsecured Revolving Credit Facility
Line of Credit Facility [Line Items]
Borrowings on lines of credit		$ 20,000,000
Unsecured Debt | Credit Suisse AG, Cayman Islands Branch [Member] | Unsecured Revolving Credit Facility
Line of Credit Facility [Line Items]
Borrowings on lines of credit				15,000,000
Unsecured Debt | Citibank, N.A. [Member] | Unsecured Revolving Credit Facility
Line of Credit Facility [Line Items]
Borrowings on lines of credit	$ 35,000,000			25,000,000
Unsecured Debt | Citibank, N.A., Credit Suisse AG, Cayman Islands Branch,an d Flagstar Bank [Member] [Member] | Unsecured Revolving Credit Facility
Line of Credit Facility [Line Items]
Borrowings on lines of credit	70,000,000	60,000,000
Line of credit, maximum borrowing capacity		110,000,000.0
Upfront fee on extended commitments									0.15%
Unsecured Debt | Other Assets | Citibank, N.A. and Credit Suisse AG, CAyman Islands Branch [Member] | Unsecured Revolving Credit Facility
Line of Credit Facility [Line Items]
Debt issuance cost				500,000
Unsecured Debt | Other Assets | Citibank, N.A., Credit Suisse AG, Cayman Islands Branch,an d Flagstar Bank [Member] [Member] | Unsecured Revolving Credit Facility
Line of Credit Facility [Line Items]
Debt issuance cost	$ 100,000	$ 200,000.0
Unsecured Debt | Maximum | Citibank, N.A. and Credit Suisse AG, CAyman Islands Branch [Member] | Unsecured Revolving Credit Facility
Line of Credit Facility [Line Items]
Borrowings on lines of credit				$ 75,000,000
Unsecured Debt | Federal Funds Rate [Domain] | Citibank, N.A. and Credit Suisse AG, CAyman Islands Branch [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate				0.50%
Unsecured Debt | London Interbank Offered Rate (LIBOR) [Member] | Citibank, N.A. and Credit Suisse AG, CAyman Islands Branch [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate				1.00%
Unsecured Debt | London Interbank Offered Rate (LIBOR) [Member] | Citibank, N.A. and Credit Suisse AG, CAyman Islands Branch [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate				2.50%
Subsequent Event | Unsecured Debt | Flagstar Bank [Member] | Unsecured Revolving Credit Facility
Line of Credit Facility [Line Items]
Borrowings on lines of credit								$ 35,000,000
Subsequent Event | Unsecured Debt | Citibank, N.A., Credit Suisse AG, Cayman Islands Branch,an d Flagstar Bank [Member] [Member] | Unsecured Revolving Credit Facility
Line of Credit Facility [Line Items]
Borrowings on lines of credit								$ 85,000,000