Total Equity - Summary of Changes in Total Equity (Detail) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Change in Stockholders' Equity
Balance at the beginning of the period			$ 492,349
Balance at the beginning of the period (in shares)			29,466
Cumulative effect from change in accounting for stock compensation	$ 15		$ 15
Walker & Dunlop net income	32,021	$ 20,153	47,479	$ 41,466
Net income (loss) from noncontrolling interests	90	$ 138	(35)	$ 138
Stock-based compensation			7,073
Issuance of common stock in connection with equity compensation plans			3,291
Repurchase and retirement of common stock			(11,979)
Other			(59)
Balance at the end of the period	$ 538,134		$ 538,134
Balance at the end of the period (in shares)	29,356		29,356
Common Stock
Change in Stockholders' Equity
Balance at the beginning of the period			$ 295
Balance at the beginning of the period (in shares)			29,466
Issuance of common stock in connection with equity compensation plans			$ 4
Issuance of common stock in connection with equity compensation plans (in shares)			415
Repurchase and retirement of common stock			$ (5)
Repurchase and retirement of common stock (in shares)			(525)
Balance at the end of the period	$ 294		$ 294
Balance at the end of the period (in shares)	29,356		29,356
Additional Paid-In Capital
Change in Stockholders' Equity
Balance at the beginning of the period			$ 215,575
Cumulative effect from change in accounting for stock compensation	$ 135		135
Stock-based compensation			7,073
Issuance of common stock in connection with equity compensation plans			3,287
Repurchase and retirement of common stock			(7,198)
Other			(54)
Balance at the end of the period	218,818		218,818
Retained Earnings
Change in Stockholders' Equity
Balance at the beginning of the period			272,030
Cumulative effect from change in accounting for stock compensation	(120)		(120)
Walker & Dunlop net income			47,479
Repurchase and retirement of common stock			(4,776)
Balance at the end of the period	314,613		314,613
Noncontrolling Interests
Change in Stockholders' Equity
Balance at the beginning of the period			4,449
Net income (loss) from noncontrolling interests			(35)
Other			(5)
Balance at the end of the period	$ 4,409		$ 4,409