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, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share [Abstract]
Net income attributable to Green Brick Partners, Inc.	$ 48,507	$ 34,819	$ 126,739	$ 84,383
Weighted-average number of shares outstanding —basic (in shares)	50,732	50,617	50,689	50,552
Basic net income attributable to Green Brick Partners, Inc. per share (in dollars per share)	$ 0.96	$ 0.69	$ 2.50	$ 1.67
Dilutive effect of stock options and restricted stock awards (in shares)	347	259	357	187
Weighted-average number of shares outstanding —diluted (in shares)	51,079	50,876	51,046	50,739
Diluted net income attributable to Green Brick Partners, Inc. per share (in dollars per share)	$ 0.95	$ 0.68	$ 2.48	$ 1.66