Results of Quarterly Operations Results of Quarterly Operations (details) (Details) - USD ($) $ / shares in Units, $ 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
Segment Reporting Information [Line Items]
Home sales revenue	$ 187,258		$ 119,874		$ 117,460		$ 79,437		$ 279,885	$ 114,622	$ 96,929	$ 69,406	$ 504,029		$ 560,842	$ 507,949
Cost of homes 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
Homebuilding gross margin	15,224		17,750		14,782		9,743		44,317	18,630	13,141	9,341	57,499		85,429	72,040
Land sale impairment													0		0	1,150
Land sales gross margin													0		0	(1,150)
Fee building revenue	42,408		39,240		38,095		43,794		44,217	43,309	47,181	55,617	163,537		190,324	186,507
Fee building	41,275		38,124		37,038		42,699		43,194	41,808	45,899	53,926	159,136		184,827	178,103
Fee building gross margin	1,133		1,116		1,057		1,095		1,023	1,501	1,282	1,691	4,401		5,497	8,404
Pretax income (loss)	(22,376)		3,400		182		(1,511)		21,692	6,974	2,505	1,360	(20,305)		32,531	33,950
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
Earnings Per Share, Basic	$ (0.80)	[1]	$ 0.12	[1]	$ 0.01	[1]	$ (0.03)	[1]	$ 0.50	$ 0.21	$ 0.07	$ 0.04	$ (0.69)	[1]	$ 0.82	$ 1.02
Earnings Per Share, Diluted	$ (0.80)		$ 0.12	[1]	$ 0.01	[1]	$ (0.03)	[1]	$ 0.50	$ 0.21	$ 0.07	$ 0.04	$ (0.69)	[1]	$ 0.82	$ 1.01
Homebuilding Segment [Member]
Segment Reporting Information [Line Items]
Home sales revenue													$ 504,029		$ 560,842	$ 507,949
Pretax income (loss)													(24,706)		27,034	25,546
Fee Building Segment [Member]
Segment Reporting Information [Line Items]
Fee building revenue													163,537		190,324	186,507
Pretax income (loss)													$ 4,401		$ 5,497	$ 8,404

[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