Settlement Assets and Obligations - Narrative (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables from agents, business solutions customers, and others, net	$ 1,613.3	$ 1,520.2
Variable rate demand notes, maximum maturity year	2052
Due after 10 years	$ 247.6
Other Assets
Accounts, Notes, Loans and Financing Receivable [Line Items]
Advances to agents	177.8	154.9
Receivables from agents and others
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables from agents, business solutions customers, and others, net	1,613.3	1,508.5
Receivables from Business Solutions customers
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables from agents, business solutions customers, and others, net		$ 11.7
State and municipal variable-rate demand notes
Accounts, Notes, Loans and Financing Receivable [Line Items]
Due after 10 years	$ 48.3