v3.5.0.2
Summary of Significant Accounting Policies New and Recently Adopted Accounting Pronouncements (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2016
Jun. 30, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]    
Unrealized Gain (Loss) on Securities $ 75 $ 128
Cetip, S.A. [Member]    
New Accounting Pronouncements or Change in Accounting Principle [Line Items]    
Available-for-sale Securities, Gross Unrealized Gain (Loss)   $ 103