QUARTERLY RESULTS (UNAUDITED) - Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Unaudited selected financial data and operating information
Loan origination and debt brokerage fees, net	$ 69,921	$ 65,144	$ 65,610	$ 57,797	$ 71,078	$ 59,594	$ 55,193	$ 48,816	$ 258,471	$ 234,681	$ 245,484
Fair value of expected net cash flows from servicing, net	47,771	50,785	41,271	40,938	53,088	39,576	47,044	32,693	180,766	172,401	193,886
Servicing fees	55,126	54,219	53,006	52,199	52,092	50,781	49,317	48,040	214,550	200,230	176,352
Total revenues	217,190	212,267	200,325	187,437	214,933	184,657	178,204	147,452	817,219	725,246	711,857
Personnel	97,082	93,057	84,398	71,631	90,828	79,776	71,426	55,273	346,168	297,303	289,277
Amortization and depreciation	39,552	37,636	37,381	37,903	36,271	36,739	35,489	33,635	152,472	142,134	131,246
Total expenses	159,216	152,952	143,347	131,353	149,603	133,998	125,234	103,561	586,868	512,396	478,196
Income from operations	57,974	59,315	56,978	56,084	65,330	50,659	52,970	43,891	230,351	212,850	233,661
Walker and Dunlop net income	$ 42,916	$ 44,043	$ 42,196	$ 44,218	$ 45,750	$ 37,716	$ 41,112	$ 36,861	$ 173,373	$ 161,439	$ 211,127
Basic EPS	$ 1.38	$ 1.42	$ 1.36	$ 1.44	$ 1.47	$ 1.20	$ 1.31	$ 1.18	$ 5.61	$ 5.15	$ 6.72
Diluted EPS	$ 1.34	$ 1.39	$ 1.33	$ 1.39	$ 1.41	$ 1.15	$ 1.26	$ 1.14	$ 5.45	$ 4.96	$ 6.47
Total originations volume	$ 9,812,055	$ 8,907,336	$ 7,306,369	$ 5,941,304	$ 9,353,456	$ 7,651,791	$ 6,193,023	$ 4,849,262
Servicing portfolio	$ 93,225,169	$ 91,754,499	$ 89,897,025	$ 87,691,682	$ 85,689,262	$ 80,485,634	$ 77,820,741	$ 75,836,280	$ 93,225,169	$ 85,689,262	$ 74,309,991