Segment Reporting (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Net fee revenues from external sources									$ 132,233	$ 122,440	$ 130,768
Net intersegment revenues									0	0	0
Net interest and dividend revenue									636	547	426
Other revenue									916	34	(258)
Total revenues	$ 33,914	$ 33,492	$ 33,756	$ 32,623	$ 31,092	$ 31,777	$ 31,023	$ 29,129	133,785	123,021	130,936
Expenses:
Depreciation and amortization									2,916	2,929	2,596
Other operating expenses									96,976	86,082	86,120
Total expenses									99,892	89,011	88,716
Income (loss) before income taxes	9,788	5,752	10,583	7,770	10,799	9,053	8,512	5,646	33,893	34,010	42,220
Income tax expense (benefit)									13,904	11,363	15,115
Net income	2,897	$ 4,132	$ 6,896	$ 6,064	7,577	$ 5,887	$ 5,661	$ 3,522	19,989	22,647	27,105
Restricted stock expense									16,430	15,954	17,574
Amortization of intangible assets									1,872	1,960	1,546
Deferred taxes on goodwill									626	547	271
Economic Earnings (Loss)									38,917	41,108	46,496
Assets	192,659				179,678				192,659	179,678	181,336
Segment goodwill	27,144				27,144				27,144	27,144	27,144
Expenditures for long-lived assets									884	1,819	816
Operating Segments | Advisory
Segment Reporting Information [Line Items]
Net fee revenues from external sources									100,612	92,127	101,973
Net intersegment revenues									8,120	7,533	19,001
Net interest and dividend revenue									546	534	425
Other revenue									911	294	(341)
Total revenues									110,189	100,488	121,058
Expenses:
Depreciation and amortization									548	575	773
Other operating expenses									58,950	50,824	63,658
Total expenses									59,498	51,399	64,431
Income (loss) before income taxes									50,691	49,089	56,627
Income tax expense (benefit)									17,120	16,331	19,330
Net income									33,571	32,758	37,297
Restricted stock expense									9,140	9,632	11,877
Amortization of intangible assets									138	160	161
Deferred taxes on goodwill									38	38	38
Economic Earnings (Loss)									42,887	42,588	49,373
Assets	207,792				174,951				207,792	174,951	183,004
Segment goodwill	5,219				5,219				5,219	5,219	5,219
Expenditures for long-lived assets									151	705	369
Operating Segments | Trust
Segment Reporting Information [Line Items]
Net fee revenues from external sources									31,621	30,313	28,795
Net intersegment revenues									218	130	0
Net interest and dividend revenue									90	13	1
Other revenue									5	(260)	83
Total revenues									31,934	30,196	28,879
Expenses:
Depreciation and amortization									1,900	1,975	1,724
Other operating expenses									28,580	27,348	25,882
Total expenses									30,480	29,323	27,606
Income (loss) before income taxes									1,454	873	1,273
Income tax expense (benefit)									(47)	426	517
Net income									1,501	447	756
Restricted stock expense									2,641	3,026	2,613
Amortization of intangible assets									1,734	1,800	1,385
Deferred taxes on goodwill									588	509	233
Economic Earnings (Loss)									6,464	5,782	4,987
Assets	69,174				67,330				69,174	67,330	60,459
Segment goodwill	21,925				21,925				21,925	21,925	21,925
Expenditures for long-lived assets									530	530	180
Westwood Holdings
Segment Reporting Information [Line Items]
Net fee revenues from external sources									0	0	0
Net intersegment revenues									0	0	0
Net interest and dividend revenue									0	0	0
Other revenue									0	0	0
Total revenues									0	0	0
Expenses:
Depreciation and amortization									468	379	99
Other operating expenses									17,784	15,573	15,581
Total expenses									18,252	15,952	15,680
Income (loss) before income taxes									(18,252)	(15,952)	(15,680)
Income tax expense (benefit)									(3,169)	(5,394)	(4,732)
Net income									(15,083)	(10,558)	(10,948)
Restricted stock expense									4,649	3,296	3,084
Amortization of intangible assets									0	0	0
Deferred taxes on goodwill									0	0	0
Economic Earnings (Loss)									(10,434)	(7,262)	(7,864)
Assets	18,437				13,985				18,437	13,985	8,816
Segment goodwill	0				0				0	0	0
Expenditures for long-lived assets									203	584	267
Eliminations
Segment Reporting Information [Line Items]
Net fee revenues from external sources									0	0	0
Net intersegment revenues									(8,338)	(7,663)	(19,001)
Net interest and dividend revenue									0	0	0
Other revenue									0	0	0
Total revenues									(8,338)	(7,663)	(19,001)
Expenses:
Depreciation and amortization									0	0	0
Other operating expenses									(8,338)	(7,663)	(19,001)
Total expenses									(8,338)	(7,663)	(19,001)
Income (loss) before income taxes									0	0	0
Income tax expense (benefit)									0	0	0
Net income									0	0	0
Restricted stock expense									0	0	0
Amortization of intangible assets									0	0	0
Deferred taxes on goodwill									0	0	0
Economic Earnings (Loss)									0	0	0
Assets	(102,744)				(76,588)				(102,744)	(76,588)	(70,943)
Segment goodwill	$ 0				$ 0				0	0	0
Expenditures for long-lived assets									$ 0	$ 0	$ 0