Net Income Attributable to Green Brick Partners, Inc. Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share [Abstract]
Net income attributable to Green Brick Partners, Inc.	$ 34,819	$ 15,671	$ 84,383	$ 42,736
Weighted-average number of shares outstanding —basic (in shares)	50,617	50,475	50,552	50,564
Basic net income attributable to Green Brick Partners, Inc. per share (in dollars per share)	$ 0.69	$ 0.31	$ 1.67	$ 0.85
Dilutive effect of stock options and restricted stock awards (in shares)	259	122	187	78
Weighted-average number of shares outstanding —diluted (in shares)	50,876	50,597	50,739	50,642
Diluted net income attributable to Green Brick Partners, Inc. per share (in dollars per share)	$ 0.68	$ 0.31	$ 1.66	$ 0.84