Settlement Assets and Obligations and Non-Settlement Related Investments - Settlement Assets and Obligations (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Settlement assets:
Cash and cash equivalents	$ 895.5	$ 1,075.7
Receivables from selling agents and Business Solutions customers	1,163.5	1,070.4
Investment securities	1,298.1	1,162.6
Total settlement assets	3,357.1	3,308.7
Settlement obligations:
Money transfer, money order and payment service payables	2,453.7	2,428.5
Payables to agents	903.4	880.2
Total settlement obligations	$ 3,357.1	$ 3,308.7