EARNINGS PER SHARE AND STOCKHOLDERS EQUITY - Basic and Diluted EPS (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Calculation of basic EPS
Walker and Dunlop net income	$ 265,762	$ 246,177	$ 173,373
Less: dividends and undistributed earnings allocated to participating securities	8,837	7,337	5,649
Net income applicable to common stockholders	$ 256,925	$ 238,840	$ 167,724
Basic weighted average shares outstanding	31,081	30,444	29,913
Basic EPS	$ 8.27	$ 7.85	$ 5.61
Calculation of diluted EPS
Add: reallocation of dividends and undistributed earnings based on assumed conversion	$ 93	$ 120	$ 126
Net income allocated to common stockholders	$ 257,018	$ 238,960	$ 167,850
Add: weighted-average diluted non-participating securities	452	639	902
Weighted average diluted shares outstanding	31,533	31,083	30,815
Diluted EPS	$ 8.15	$ 7.69	$ 5.45