Note 12 - Related Party Transactions (Details Textual)			3 Months Ended				12 Months Ended
	Mar. 01, 2019 USD ($)	Jun. 26, 2015 USD ($)	Dec. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2018	Mar. 31, 2018 USD ($)	Sep. 30, 2017 USD ($)
Due from Affiliates			$ 102,000				$ 102,000	$ 238,000
Equity Method Investments			2,107,000				2,107,000	30,217,000
Income (Loss) from Equity Method Investments, Total							(18,791,000)	(3,503,000)	$ (19,653,000)
Revenue from Contract with Customer, Including Assessed Tax							507,411,000	669,349,000	667,566,000
Bedford 2 [Member]
Equity Method Investment, Other than Temporary Impairment							$ 2,300,000
Proceeds from Sale of Equity Method Investments				$ 5,100,000
Joint Venture, Option Rights, Percentage							30.00%
Unconsolidated Joint Ventures [Member]
Equity Method Investment, Other than Temporary Impairment					$ 20,000,000.0	$ 2,300,000	$ 22,300,000	0	1,100,000
Income (Loss) from Equity Method Investments, Total			4,500,000
Proceeds from Sale of Equity Method Investments				$ 5,100,000
Interest Income on Note to Joint Venture [Member] | Encore McKinley [Member]
Debt Instrument, Interest Rate, Stated Percentage													10.00%
Interest Income, Related Party									100,000
Corporate Joint Venture [Member] | Construction-related Costs [Member]
Related Party Transaction, Expenses from Transactions with Related Party							2,900,000	5,500,000	6,400,000
Due from Affiliates			100,000				100,000	200,000
Corporate Joint Venture [Member] | Management Fees [Member]
Due from Affiliates			$ 36,000				36,000	0
Revenue from Related Parties							$ 900,000	1,900,000	3,400,000
Related Party [Member]
Common Stock Beneficial Ownership Percentage, Significant Amount Threshold			10.00%				10.00%
TNHC Merdian Investors LLC, and TNHC Russel Ranch LLC [Member]
Equity Method Investments			$ 100,000				$ 100,000	13,700,000
Director [Member] | Russel Ranch [Member]
Purchase Options, Land															$ 34,000,000.0
IHP [Member] | LLC Agreement of Russell Ranch [Member]
Joint Venture Agreement, Additional Required Capital Agreed to Fund												$ 26,000,000
Joint Venture Agreement, Additional Required Capital Agreed to Fund, Percentage Funded by Related Party												50.00%
Joint Venture Agreement, Additional Required Capital Agreed to Fund, Percentage Funded by Entity												50.00%
TL Fab LP [Member] | Trade Payment [Member]
Related Party Transaction, Amounts of Transaction							13,000	200,000	300,000
Accounts Payable, Related Parties			0				0	0
TL Fab LP [Member] | Trade Payment [Member] | Unconsolidated Joint Ventures [Member]
Related Party Transaction, Amounts of Transaction							0	0	400,000
Accounts Payable, Related Parties			0				0	0
TNHC-HW Cannery LLC [Member]
Due from Affiliates			0				0	15,000
Deferred Profit From Lot Transactions			100,000				100,000	200,000
Land Owner Fees Reimbursed							15,000	100,000	100,000
Consultant Davis [Member]
Due from Affiliates			0				0	0
Consultant Davis [Member] | Fee Building Revenue [Member]
Revenue from Contract with Customer, Including Assessed Tax							0	500,000	3,000,000.0
Cost of Goods and Services Sold, Total							0	500,000	2,900,000
Consultant Davis [Member] | General Contractor [Member]
Revenue from Contract with Customer, Including Assessed Tax							0	15,000	83,000
Consultant Davis [Member] | Monthly Consulting Fee [Member]
Related Party Transaction, Amounts of Transaction		$ 5,000					1,000
Accounts Payable, Related Parties			0				0	0
Consultant Stelmar [Member] | Monthly Consulting Fee [Member]
Related Party Transaction, Amounts of Transaction							0	$ 48,000	$ 90,000
Consultant Redwitz [Member]
Related Party Transaction, Amounts of Transaction							5,000
Consultant Redwitz [Member] | Monthly Consulting Fee [Member]
Related Party Transaction, Amounts of Transaction	$ 10,000
Accounts Payable, Related Parties			0				0
10% Common Stock Affiliate [Member] | Northern CA Phased Takedown [Member]
Purchase Options, Land										$ 16,100,000
Percentage of Optioned Lots Taken Down								34.00%	34.00%
Master Marketing Fees							500,000
10% Common Stock Affiliate [Member] | Northern CA Rolling Option [Member]
Land Owner Fees Reimbursed							200,000
Percentage of Optioned Lots Taken Down								26.00%	8.00%
Estimated Purchase Price										$ 56,300,000
Percentage of Lots Agreed to Be Purchased by Unrelated Third Party								67.00%
Number of Lots Remaining to Purchase From Affiliate								0
Deposit Assets, Total			0				0
Option Payment							3,000,000.0
Amounts Paid for Purchase of Lots							18,000,000.0
10% Common Stock Affiliate [Member] | Northern California Finished Lots [Member]
Purchase Options, Land									$ 8,000,000.0
Master Marketing Fees							300,000
Reimbursed Costs							$ 200,000
10% Common Stock Affiliate [Member] | Arizona Master Plan [Member]
Purchase Options, Land									$ 3,800,000
Percentage of Optioned Lots Taken Down							38.00%
Master Marketing Fees							$ 22,000
Deposits Assets			200,000				200,000	$ 300,000
Bedford [Member]
Purchase Options, Land											$ 9,300,000			$ 10,000,000.0
Percentage of Optioned Lots Taken Down								46.00%	54.00%
Master Marketing Fees							200,000
Deposits Assets								$ 1,500,000
Board Affiliate [Member] | Bedford 2 [Member]
Purchase Options, Land			10,500,000				$ 10,500,000
Percentage of Optioned Lots Taken Down							8.00%	92.00%
Master Marketing Fees							$ 300,000
Deposits Assets									$ 1,400,000
Deposit Assets Outstanding			$ 0				$ 0	$ 0
Fidelity [Member] | Payments for Record Keeping and Investment Management Services [Member]
Defined Contribution Plan, Record Keeping and Investment Management Services Paid by the Company									14,000
Defined Contribution Plan, Record Keeping and Investment Management Services Paid by the Participants									$ 6,000