Segregated Cash (Notes)

9 Months Ended

Sep. 30, 2017

Segregated Cash [Abstract]

Restricted Assets Disclosure [Text Block]

Segregated Cash

As of September 30, 2017 and December 31, 2016, cash segregated in compliance with federal regulations and other restricted deposits of $140.7 million and $1.0 million, respectively, consisted of cash deposited in special bank accounts for the benefit of customers under SEC Rule 15c3-3 and cash held in accounts designated as Special Reserve Bank Accounts for Proprietary Accounts of Broker-Dealers (PAB).