Supplemental Guarantor Information Supplemental Condensed Consolidating Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Home sales	$ 187,258	$ 119,874	$ 117,460	$ 79,437	$ 279,885	$ 114,622	$ 96,929	$ 69,406	$ 504,029	$ 560,842	$ 507,949
Fee building, including management fees from unconsolidated joint ventures of $3,385, $4,945 and $8,202, respectively	42,408	39,240	38,095	43,794	44,217	43,309	47,181	55,617	163,537	190,324	186,507
Revenue, Net									667,566	751,166	694,456
Home sales	162,034	102,124	102,678	69,694	234,668	95,992	82,488	60,065	436,530	473,213	433,559
Home sales impairments	10,000	0	0	0	900	0	1,300	0	10,000	2,200	2,350
Impairment of Real Estate Land									0	0	1,150
Fee building	41,275	38,124	37,038	42,699	43,194	41,808	45,899	53,926	159,136	184,827	178,103
Cost of Sales									605,666	660,240	615,162
Gross Profit Home Sales	15,224	17,750	14,782	9,743	44,317	18,630	13,141	9,341	57,499	85,429	72,040
Gross Profit Fee Building	1,133	1,116	1,057	1,095	1,023	1,501	1,282	1,691	4,401	5,497	8,404
Gross Profit Land Sales									0	0	(1,150)
Gross Profit									61,900	90,926	79,294
Selling and marketing expenses									(36,065)	(32,702)	(26,744)
General and administrative expenses									(25,966)	(26,330)	(25,882)
Equity in net income (loss) of unconsolidated joint ventures									(19,653)	866	7,691
Equity in net income (loss) of subsdiaries									0	0	0
Other income (expense), net									(521)	(229)	(409)
Pretax income (loss)	(22,376)	3,400	182	(1,511)	21,692	6,974	2,505	1,360	(20,305)	32,531	33,950
(Provision) benefit for income taxes									6,075	(15,390)	(13,024)
Net income (loss)									(14,230)	17,141	20,926
Net loss attributable to non-controlling interest									14	11	96
Net Income (Loss) Attributable to The New Home Company Inc.	(16,150)	$ 2,459	$ 115	$ (640)	10,471	$ 4,318	$ 1,517	$ 846	(14,216)	17,152	21,022
Cash and cash equivalents	42,273				123,546				42,273	123,546	30,496
Guarantor Subsidiaries [Member]
Home sales									504,029	560,842	502,792
Fee building, including management fees from unconsolidated joint ventures of $3,385, $4,945 and $8,202, respectively									163,537	190,324	186,662
Revenue, Net									667,566	751,166	689,454
Home sales									436,508	473,181	428,881
Home sales impairments									10,000	2,200	2,350
Impairment of Real Estate Land											1,150
Fee building									159,136	184,827	175,863
Cost of Sales									605,644	660,208	608,244
Gross Profit Home Sales									57,521	85,461	71,561
Gross Profit Fee Building									4,401	5,497	10,799
Gross Profit Land Sales											(1,150)
Gross Profit									61,922	90,958	81,210
Selling and marketing expenses									(36,065)	(32,702)	(26,058)
General and administrative expenses									(30,293)	(23,927)	(11,163)
Equity in net income (loss) of unconsolidated joint ventures									(19,653)	866	7,691
Equity in net income (loss) of subsdiaries									0	0	0
Other income (expense), net									(455)	(336)	(303)
Pretax income (loss)									(24,544)	34,859	51,377
(Provision) benefit for income taxes									(7,183)	13,065	19,033
Net income (loss)									(17,361)	21,794	32,344
Net loss attributable to non-controlling interest									0	0	0
Net Income (Loss) Attributable to The New Home Company Inc.									(17,361)	21,794	32,344
Cash and cash equivalents	13,249				23,772				13,249	23,772
Non-Guarantor Subsidiaries [Member]
Home sales									0	0	5,157
Fee building, including management fees from unconsolidated joint ventures of $3,385, $4,945 and $8,202, respectively									0	0	0
Revenue, Net									0	0	5,157
Home sales									22	32	4,678
Home sales impairments									0	0	0
Impairment of Real Estate Land											0
Fee building									0	0	0
Cost of Sales									22	32	4,678
Gross Profit Home Sales									(22)	(32)	479
Gross Profit Fee Building									0	0	0
Gross Profit Land Sales											0
Gross Profit									(22)	(32)	479
Selling and marketing expenses									0	0	(686)
General and administrative expenses									(3)	0	0
Equity in net income (loss) of unconsolidated joint ventures									0	0	0
Equity in net income (loss) of subsdiaries									0	0	0
Other income (expense), net									0	0	(142)
Pretax income (loss)									(25)	(32)	(349)
(Provision) benefit for income taxes									0	0	0
Net income (loss)									(25)	(32)	(349)
Net loss attributable to non-controlling interest									14	11	96
Net Income (Loss) Attributable to The New Home Company Inc.									(11)	(21)	(253)
Cash and cash equivalents	147				188				147	188
Parent Company [Member]
Home sales									0	0	0
Fee building, including management fees from unconsolidated joint ventures of $3,385, $4,945 and $8,202, respectively									0	0	0
Revenue, Net									0	0	0
Home sales									0	0	0
Home sales impairments									0	0	0
Impairment of Real Estate Land											0
Fee building									0	0	2,240
Cost of Sales									0	0	2,240
Gross Profit Home Sales									0	0	0
Gross Profit Fee Building									0	0	(2,240)
Gross Profit Land Sales											0
Gross Profit									0	0	(2,240)
Selling and marketing expenses									0	0	0
General and administrative expenses									4,330	(2,403)	(14,719)
Equity in net income (loss) of unconsolidated joint ventures									0	0	0
Equity in net income (loss) of subsdiaries									(17,372)	21,773	32,091
Other income (expense), net									(66)	107	(119)
Pretax income (loss)									(13,108)	19,477	15,013
(Provision) benefit for income taxes									1,108	2,325	(6,009)
Net income (loss)									(14,216)	17,152	21,022
Net loss attributable to non-controlling interest									0	0	0
Net Income (Loss) Attributable to The New Home Company Inc.									(14,216)	17,152	21,022
Cash and cash equivalents	28,877				99,586				28,877	99,586
Consolidation, Eliminations [Member]
Home sales									0	0	0
Fee building, including management fees from unconsolidated joint ventures of $3,385, $4,945 and $8,202, respectively									0	0	(155)
Revenue, Net									0	0	(155)
Home sales									0	0	0
Home sales impairments									0	0	0
Impairment of Real Estate Land											0
Fee building									0	0	0
Cost of Sales									0	0	0
Gross Profit Home Sales									0	0	0
Gross Profit Fee Building									0	0	(155)
Gross Profit Land Sales											0
Gross Profit									0	0	(155)
Selling and marketing expenses									0	0	0
General and administrative expenses									0	0	0
Equity in net income (loss) of unconsolidated joint ventures									0	0	0
Equity in net income (loss) of subsdiaries									17,372	(21,773)	(32,091)
Other income (expense), net									0	0	155
Pretax income (loss)									17,372	(21,773)	(32,091)
(Provision) benefit for income taxes									0	0	0
Net income (loss)									17,372	(21,773)	(32,091)
Net loss attributable to non-controlling interest									0	0	0
Net Income (Loss) Attributable to The New Home Company Inc.									17,372	(21,773)	$ (32,091)
Cash and cash equivalents	$ 0				$ 0				$ 0	$ 0