Consolidated Statements of Financial Condition - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Assets
Financial Designation, Predecessor and Successor [Fixed List]	Successor	Successor	Successor	Successor
Cash and cash equivalents	$ 410,104	$ 460,711	$ 460,711	$ 410,104
Restricted cash	1,200	1,000	1,000	1,200
Receivable from brokers and dealers and clearing organizations	174,591	30,641	30,641	174,591
Deposits with clearing organizations	11,427	9,724	9,724	11,427
Accounts receivable, net of allowance	87,192	92,814	92,814	87,192
Furniture, equipment, purchased software and leasehold improvements, net of accumulated depreciation and amortization	38,128	40,405	40,405	38,128
Right-of-use assets		24,504	24,504
Software development costs, net of accumulated amortization	170,582	173,086	173,086	170,582
Goodwill	2,694,797	2,694,797	2,694,797	2,694,797
Intangible assets, net of accumulated amortization	1,380,848	1,281,441	1,281,441	1,380,848
Receivable from affiliates	3,243	2,525	2,525	3,243
Deferred tax asset		256,450	256,450
Other assets	25,027	27,236	27,236	25,027
Total assets	4,997,139	5,095,334	5,095,334	4,997,139
Liabilities
Payable to brokers and dealers and clearing organizations	171,214	30,452	30,452	171,214
Accrued compensation	120,158	119,415	119,415	120,158
Deferred revenue	27,883	23,990	23,990	27,883
Accounts payable, accrued expenses and other liabilities	42,548	32,834	32,834	42,548
Employee equity compensation payable	24,187	1,048	1,048	24,187
Lease liability		30,955	30,955
Payable to affiliates	5,009	1,506	1,506	5,009
Deferred tax liability	19,627	21,572	21,572	19,627
Tax receivable agreement liability		240,817	240,817
Total liabilities	410,626	502,589	502,589	410,626
Commitments and contingencies (Note 17)
Mezzanine Capital
Class C Shares and Class P(C) Shares	14,179			14,179
Stockholders' Equity/Members' Capital
Members’ capital	4,573,200			4,573,200
Preferred stock, $.00001 par value; 250,000,000 shares authorized; none issued or outstanding
Additional paid-in capital		3,329,386	3,329,386
Accumulated other comprehensive income (loss)	(866)	1,366	1,366	(866)
Retained earnings		47,833	47,833
Total stockholders' equity attributable to Tradeweb Markets Inc./members' capital	4,572,334	3,378,588	3,378,588	4,572,334
Non-controlling interests		1,214,157	1,214,157
Total equity	4,572,334	4,592,745	4,592,745	4,572,334
Total liabilities and stockholders' equity/members' capital	$ 4,997,139	5,095,334	5,095,334	$ 4,997,139
Class A common stock
Stockholders' Equity/Members' Capital
Common stock		1	1
Total equity		1	1
Class B common stock
Stockholders' Equity/Members' Capital
Common stock		1	1
Total equity		1	1
Class D common stock
Stockholders' Equity/Members' Capital
Common stock		1	1
Total equity		$ 1	$ 1
Tradeweb Markets LLC
Assets
Financial Designation, Predecessor and Successor [Fixed List]	Successor