EARNINGS PER SHARE - Basic and Diluted EPS (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Calculation of basic EPS
Walker and Dunlop net income	$ 62,059	$ 47,829	$ 42,196	$ 44,218	$ 109,888	$ 86,414
Less: dividends and undistributed earnings allocated to participating securities	1,873		1,328		3,392	2,835
Net income applicable to common stockholders	$ 60,186		$ 40,868		$ 106,496	$ 83,579
Basic weighted average shares outstanding	30,352		29,985		30,288	29,834
Basic EPS	$ 1.98		$ 1.36		$ 3.52	$ 2.80
Calculation of diluted EPS
Add: reallocation of dividends and undistributed earnings based on assumed conversion	$ 25		$ 25		$ 57	$ 62
Net income allocated to common stockholders	$ 60,211		$ 40,893		$ 106,553	$ 83,641
Add: weighted-average diluted non-participating securities	508		759		672	886
Weighted average diluted shares outstanding	30,860		30,744		30,960	30,720
Diluted EPS	$ 1.95		$ 1.33		$ 3.44	$ 2.72
Shares outstanding excluded from computation of earnings per share	537