Derivative Instruments and Hedging Activities (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Ria Operations [Member] | Foreign Exchange Contracts [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Notional Amount	$ 188,000		$ 188,000
HiFX Operations [Member] | Foreign Exchange Contracts [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Notional Amount	849,000		$ 849,000
Maximum [Member] | Ria Operations [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Foreign currency forward contract term			14 days
Trading Revenue [Member] | HiFX Operations [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Foreign Currency Exchange Margin	$ 15,500	$ 15,900	$ 47,100	$ 23,000