ACQUISITIONS - Pro Forma Information (Details) - Acquisition #4 - Alliant Capital - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Supplementary pro forma information
Revenues	$ 1,387,227	$ 1,187,820
Income from operations	391,237	361,489
Walker and Dunlop net income	$ 293,062	$ 277,400
Earnings per share	$ 8.90	$ 8.62
Diluted earnings per share	$ 8.78	$ 8.45
Weighted average earnings shares outstanding	31,856	31,253
Weighted average diluted shares outstanding	32,308	31,892
Acquisition-Related Adjustments
Supplementary pro forma information
Income from operations	$ (9,700)	$ (7,300)
Walker and Dunlop net income	$ (21,600)	$ (12,900)