Results of Quarterly Operations Results of Quarterly Operations (details) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2017		Sep. 30, 2017		Jun. 30, 2017		Mar. 31, 2017		Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017		Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Home sales revenue	$ 279,885		$ 114,622		$ 96,929		$ 69,406		$ 261,668	$ 125,142	$ 78,836	$ 42,303	$ 560,842		$ 507,949	$ 280,209
Cost of homes sales	234,668		95,992		82,488		60,065		221,700	105,799	69,390	36,670	473,213		433,559	235,232
Home sales impairments	900		0		1,300		0		2,350	0	0	0	2,200		2,350	0
Homebuilding gross margin	44,317		18,630		13,141		9,341		37,618	19,343	9,446	5,633	85,429		72,040	44,977
Land sale impairment									1,150	0	0	0	0		1,150	0
Land sales gross margin									(1,150)	0	0	0	0		(1,150)	0
Fee building revenue	44,217		43,309		47,181		55,617		60,781	52,761	30,028	42,937	190,324		186,507	149,890
Fee building	43,194		41,808		45,899		53,926		58,040	50,832	28,317	40,914	184,827		178,103	139,677
Fee building gross margin	1,023		1,501		1,282		1,691		2,741	1,929	1,711	2,023	5,497		8,404	10,213
Pretax income	21,692		6,974		2,505		1,360		22,080	9,042	3,939	(1,111)	32,531		33,950	33,911
Net income attributable to The New Home Company Inc.	$ 10,471		$ 4,318		$ 1,517		$ 846		$ 13,780	$ 5,547	$ 2,509	$ (814)	$ 17,152		$ 21,022	$ 21,688
Earnings Per Share, Basic	$ 0.50	[1]	$ 0.21	[1]	$ 0.07	[1]	$ 0.04	[1]	$ 0.67	$ 0.27	$ 0.12	$ (0.04)	$ 0.82	[1]	$ 1.02	$ 1.29
Earnings Per Share, Diluted	$ 0.50	[1]	$ 0.21	[1]	$ 0.07	[1]	$ 0.04	[1]	$ 0.66	$ 0.27	$ 0.12	$ (0.04)	$ 0.82	[1]	$ 1.01	$ 1.28
Homebuilding Segment [Member]
Segment Reporting Information [Line Items]
Home sales revenue													$ 560,842		$ 507,949	$ 280,209
Pretax income													27,034		25,546	23,698
Fee Building Segment [Member]
Segment Reporting Information [Line Items]
Fee building revenue													190,324		186,507	149,890
Pretax income													$ 5,497		$ 8,404	$ 10,213

[1] (1)Some amounts do not add to our full year results presented on our consolidated statement of operations due to rounding differences in quarterly and annual weighted average share calculations