Regulatory Capital Requirements (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
TWL
Regulatory Capital Requirements
Regulatory Capital	$ 62,001	$ 42,317
Regulatory Capital Requirement	1,710	2,396
Excess Regulatory Capital	60,291	39,921
DW
Regulatory Capital Requirements
Regulatory Capital	58,727	52,016
Regulatory Capital Requirement	1,805	2,026
Excess Regulatory Capital	56,922	49,990
TWD
Regulatory Capital Requirements
Regulatory Capital	23,509	33,807
Regulatory Capital Requirement	634	664
Excess Regulatory Capital	22,875	33,143
TEL
Regulatory Capital Requirements
Regulatory Capital	52,520	49,611
Regulatory Capital Requirement	31,953	21,856
Excess Regulatory Capital	20,567	27,755
TWJ
Regulatory Capital Requirements
Regulatory Capital	10,956	11,851
Regulatory Capital Requirement	3,714	8,565
Excess Regulatory Capital	7,242	3,286
TWEU
Regulatory Capital Requirements
Regulatory Capital	5,936	6,217
Regulatory Capital Requirement	1,773	1,701
Excess Regulatory Capital	4,163	4,516
TW SEF
Regulatory Capital Requirements
Financial Resources	26,831	21,303
Required Financial Resources	13,500	10,500
Excess Financial Resources	13,331	10,803
Liquid Financial Assets	14,012	18,168
Required Liquid Financial Assets	6,750	5,250
Excess Liquid Financial Assets	7,262	12,918
DW SEF
Regulatory Capital Requirements
Financial Resources	13,898	13,707
Required Financial Resources	5,595	5,505
Excess Financial Resources	8,303	8,202
Liquid Financial Assets	7,564	7,583
Required Liquid Financial Assets	2,798	2,753
Excess Liquid Financial Assets	$ 4,766	$ 4,830