Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Assets:
Settlement assets	$ 2,999.5	$ 2,843.5
Derivatives	139.5	247.7
Liabilities:
Derivatives	114.0	183.8
Recurring
Assets:
Derivatives	139.5	247.7
Total assets	1,548.5	1,654.5
Liabilities:
Derivatives	114.0	183.8
Total liabilities	114.0	183.8
Recurring \| Money market funds
Assets:
Settlement assets	6.7	7.9
Recurring \| State and municipal debt securities
Assets:
Settlement assets	1,232.0	1,219.9
Recurring \| State and municipal variable rate demand notes
Assets:
Settlement assets	79.9	84.8
Recurring \| Corporate debt securities
Assets:
Settlement assets	58.9
Recurring \| Corporate and other debt securities
Assets:
Settlement assets		57.8
Recurring \| United States government agency mortgage-backed securities
Assets:
Settlement assets	31.5	36.4
Recurring \| Level 1
Assets:
Total assets	6.7	7.9
Recurring \| Level 1 \| Money market funds
Assets:
Settlement assets	6.7	7.9
Recurring \| Level 2
Assets:
Derivatives	139.5	247.7
Total assets	1,541.8	1,646.6
Liabilities:
Derivatives	114.0	183.8
Total liabilities	114.0	183.8
Recurring \| Level 2 \| State and municipal debt securities
Assets:
Settlement assets	1,232.0	1,219.9
Recurring \| Level 2 \| State and municipal variable rate demand notes
Assets:
Settlement assets	79.9	84.8
Recurring \| Level 2 \| Corporate debt securities
Assets:
Settlement assets	58.9
Recurring \| Level 2 \| Corporate and other debt securities
Assets:
Settlement assets		57.8
Recurring \| Level 2 \| United States government agency mortgage-backed securities
Assets:
Settlement assets	$ 31.5	$ 36.4

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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