TOTAL EQUITY - Summary of Changes in Total Equity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Change in Stockholders' Equity
Balances at the beginning of the period	$ 964,235	$ 928,072	$ 907,192	$ 873,621	$ 832,267	$ 814,981	$ 907,192	$ 814,981
Balance at the beginning of the period (in shares)			29,497				29,497
Cumulative effect adjustment for adoption of ASU 2016-02			$ (1,002)
Walker and Dunlop net income	44,043	42,196	44,218	37,716	41,112	36,861	$ 130,457	115,689
Net income (loss) from noncontrolling interests	26	(50)	(158)	41	(79)	(154)	(182)	(192)
Contributions from noncontrolling interests	1,549
Other comprehensive income (loss), net of tax	123	666	301	16	(53)	(127)
Stock-based compensation - equity classified	5,242	4,417	6,812	7,319	5,076	5,093
Issuance of common stock in connection with equity compensation plans	266	1	4,187	929	3,159	4,851
Repurchase and retirement of common stock	(3,936)	(1,756)	(24,159)	(5,312)		(21,400)
Cash dividends paid	(9,306)	(9,311)	(9,319)	(7,901)	(7,861)	(7,838)
Balances at the end of the period	$ 1,002,242	$ 964,235	$ 928,072	$ 906,429	$ 873,621	$ 832,267	$ 1,002,242	906,429
Balance at the end of the period (in shares)	29,957						29,957
Cash dividends paid per common share	$ 0.30	$ 0.30	$ 0.30	$ 0.25	$ 0.25	$ 0.25
Common Stock
Change in Stockholders' Equity
Balances at the beginning of the period	$ 300	$ 300	$ 295	$ 304	$ 301	$ 300	$ 295	$ 300
Balance at the beginning of the period (in shares)	29,964	29,973	29,497	30,390	30,148	30,016	29,497	30,016
Issuance of common stock in connection with equity compensation plans	$ 1	$ 1	$ 9	$ 1	$ 3	$ 5
Issuance of common stock in connection with equity compensation plans (in shares)	68	24	935	104	242	567
Repurchase and retirement of common stock	$ (1)	$ (1)	$ (4)	$ (1)		$ (4)
Repurchase and retirement of common stock (in shares)	(75)	(33)	(459)	(97)		(435)
Balances at the end of the period	$ 300	$ 300	$ 300	$ 304	$ 304	$ 301	$ 300	$ 304
Balance at the end of the period (in shares)	29,957	29,964	29,973	30,397	30,390	30,148	29,957	30,397
APIC
Change in Stockholders' Equity
Balances at the beginning of the period	$ 227,621	$ 223,742	$ 235,152	$ 234,564	$ 226,332	$ 229,080	$ 235,152	$ 229,080
Stock-based compensation - equity classified	5,242	4,417	6,812	7,319	5,076	5,093
Issuance of common stock in connection with equity compensation plans	265		4,178	928	3,156	4,846
Repurchase and retirement of common stock	(1,831)	(538)	(22,400)	(2,090)		(12,687)
Balances at the end of the period	231,297	227,621	223,742	240,721	234,564	226,332	231,297	240,721
AOCI
Change in Stockholders' Equity
Balances at the beginning of the period	892	226	(75)	(87)	(34)	93	(75)	93
Other comprehensive income (loss), net of tax	123	666	301	16	(53)	(127)
Balances at the end of the period	1,015	892	226	(71)	(87)	(34)	1,015	(71)
Retained Earnings
Change in Stockholders' Equity
Balances at the beginning of the period	730,562	698,894	666,752	633,508	600,257	579,943	666,752	579,943
Cumulative effect adjustment for adoption of ASU 2016-02			(1,002)
Walker and Dunlop net income	44,043	42,196	44,218	37,716	41,112	36,861
Repurchase and retirement of common stock	(2,104)	(1,217)	(1,755)	(3,221)		(8,709)
Cash dividends paid	(9,306)	(9,311)	(9,319)	(7,901)	(7,861)	(7,838)
Balances at the end of the period	763,195	730,562	698,894	660,102	633,508	600,257	763,195	660,102
Noncontrolling Interests
Change in Stockholders' Equity
Balances at the beginning of the period	4,860	4,910	5,068	5,332	5,411	5,565	5,068	5,565
Net income (loss) from noncontrolling interests	26	(50)	(158)	41	(79)	(154)
Contributions from noncontrolling interests	1,549
Balances at the end of the period	$ 6,435	$ 4,860	$ 4,910	$ 5,373	$ 5,332	$ 5,411	$ 6,435	$ 5,373