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Revenue from Contracts with Clients (Narrative) (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Dec. 31, 2017
Disaggregation of Revenue [Line Items]          
Security commissions and trading income $ 26.1 $ 24.1 $ 53.3 $ 44.6  
Other operating income 31.4   66.2    
Estate settlement revenue transition adjustment         $ 2.7
Securities Commissions and Trading Income          
Disaggregation of Revenue [Line Items]          
Revenue from contract with client 22.3   46.3    
Other Operating Income          
Disaggregation of Revenue [Line Items]          
Revenue from contract with client $ 11.6   $ 22.9