Investments 4 (Details) - CME Rights Offering $ / shares in Units, warrant in Millions, $ in Millions	Sep. 30, 2016 USD ($) warrant $ / shares shares
Class of Warrant or Right [Line Items]
Economic interest (percent)	76.00%
Class of warrant or right, number of securities called by each warrant or right (shares) | shares	1
Class of warrant or right, term (years)	4 years
Class of warrant or right, exercise price of warrants or rights (in dollars per share) | $ / shares	$ 1
Warrant
Class of Warrant or Right [Line Items]
Warrants Held | warrant	101
Equity warrants | $	$ 135