Significant Accounting Policies (Schedule of Basic and Diluted Net Income) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ 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
Net income attributable to Green Brick Partners, Inc. per share
Net income attributable to Green Brick Partners, Inc.	$ (8,196)	$ 9,280	$ 7,689	$ 6,197	$ 7,676	$ 6,243	$ 6,743	$ 3,094	$ 14,970	$ 23,756	$ 15,325
Weighted-average number of shares outstanding - basic (in shares)									49,597	48,879	40,068
Basic net income attributable to Green Brick Partners, Inc. per share (in dollars per share)	$ (0.16)	$ 0.19	$ 0.16	$ 0.13	$ 0.16	$ 0.13	$ 0.14	$ 0.06	$ 0.30	$ 0.49	$ 0.38
Diluted net income attributable to Green Brick Partners, Inc. per share
Weighted-average number of shares outstanding - diluted (in shares)									49,683	48,886	40,099
Weighted Average Number Diluted Shares Outstanding Adjustment									86	7	30
Diluted net income attributable to Green Brick Partners, Inc. per share (in dollars per share)	$ (0.16)	$ 0.19	$ 0.16	$ 0.13	$ 0.16	$ 0.13	$ 0.14	$ 0.06	$ 0.30	$ 0.49	$ 0.38