ITG Acquisition - Background (Details)	Mar. 01, 2019 USD ($)
Committed facility
Business Acquisition [Line Items]
Maximum borrowing capacity	$ 50,000,000
Letter of credit
Business Acquisition [Line Items]
Maximum borrowing capacity	5,000,000
Swingline subfacility
Business Acquisition [Line Items]
Maximum borrowing capacity	5,000,000
First lien term loan
Business Acquisition [Line Items]
Face amount	1,500,000,000
Proceeds from borrowings	404,500,000
First lien term loan | ITG
Business Acquisition [Line Items]
Proceeds from borrowings	$ 1,095,000,000