Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Assets:
Settlement assets	$ 2,843.5	$ 3,821.4
Derivatives	247.7	453.3
Liabilities:
Derivatives	183.8	430.3
Recurring
Assets:
Derivatives	247.7	453.3
Total assets	1,654.5	2,457.0
Liabilities:
Derivatives	183.8	430.3
Total liabilities	183.8	430.3
Recurring \| Money market funds
Assets:
Settlement assets	7.9	13.1
Recurring \| State and municipal debt securities
Assets:
Settlement assets	1,219.9	1,303.9
Recurring \| State and municipal variable rate demand notes
Assets:
Settlement assets	84.8	562.1
Recurring \| United States government agency mortgage-backed securities
Assets:
Settlement assets	36.4	51.8
Recurring \| Corporate and other debt securities
Assets:
Settlement assets	57.8	72.8
Recurring \| Level 1
Assets:
Total assets	7.9	13.1
Recurring \| Level 1 \| Money market funds
Assets:
Settlement assets	7.9	13.1
Recurring \| Level 2
Assets:
Derivatives	247.7	453.3
Total assets	1,646.6	2,443.9
Liabilities:
Derivatives	183.8	430.3
Total liabilities	183.8	430.3
Recurring \| Level 2 \| State and municipal debt securities
Assets:
Settlement assets	1,219.9	1,303.9
Recurring \| Level 2 \| State and municipal variable rate demand notes
Assets:
Settlement assets	84.8	562.1
Recurring \| Level 2 \| United States government agency mortgage-backed securities
Assets:
Settlement assets	36.4	51.8
Recurring \| Level 2 \| Corporate and other debt securities
Assets:
Settlement assets	$ 57.8	$ 72.8

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Cash received or short term receivables for unsettled money transfers, money orders, consumer payments, or business to business payments. Settlement assets include clearing and settling customers payments due to and from financial institutions and may include cash and cash equivalents.

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