| Securities under repurchase agreement obligations | 
    |   | 
      | 
    June 30, 2018 | 
      | 
 
    |   | 
      | 
    Interest rates and remaining contractual maturity of the agreements | 
      | 
 
    |   | 
      | 
    Average interest rate | 
      | 
      | 
    Up to 30 days | 
      | 
      | 
    30-90 days | 
      | 
      | 
    Over 90 days | 
      | 
      | 
    Total | 
      | 
 
    |   | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
 
    | Securities sold under repurchase agreements | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
 
    | Corporate equity | 
      | 
      | 
    12.26 | 
    % | 
      | 
    $ | 
    86,961 | 
      | 
      | 
    $ | 
    906 | 
      | 
      | 
    $ | 
    6,532 | 
      | 
      | 
    $ | 
    94,399 | 
      | 
 
    | Corporate debt | 
      | 
      | 
    6.83 | 
    % | 
      | 
      | 
    9,896 | 
      | 
      | 
      | 
    - | 
      | 
      | 
      | 
    - | 
      | 
      | 
      | 
    9,896 | 
      | 
 
    | Non-US sovereign debt | 
      | 
      | 
    8.41 | 
    % | 
      | 
      | 
    10,277 | 
      | 
      | 
      | 
    - | 
      | 
      | 
      | 
    - | 
      | 
      | 
      | 
    10,277 | 
      | 
 
    | Total securities sold under repurchase agreements | 
      | 
      | 
      | 
      | 
      | 
    $ | 
    107,134 | 
      | 
      | 
    $ | 
    906 | 
      | 
      | 
    $ | 
    6,532 | 
      | 
      | 
    $ | 
    114,572 | 
      | 
 
 
  
    |   | 
      | 
    March 31, 2018 (Recast) | 
      | 
 
    |   | 
      | 
    Interest rate and remaining contractual maturity of the agreements | 
      | 
 
    |   | 
      | 
    Average interest rate | 
      | 
      | 
    Overnight and continuous | 
      | 
      | 
    Up to 30 days | 
      | 
      | 
    30-90 days | 
      | 
      | 
    Total | 
      | 
 
    |   | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
 
    | Securities sold under repurchase agreements | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
 
    | Corporate equity | 
      | 
      | 
    12.04 | 
    % | 
      | 
    $ | 
    109,821 | 
      | 
      | 
    $ | 
    8,961 | 
      | 
      | 
    $ | 
    7,148 | 
      | 
      | 
    $ | 
    125,930 | 
      | 
 
    | Corporate debt | 
      | 
      | 
    10.64 | 
    % | 
      | 
      | 
    24,257 | 
      | 
      | 
      | 
    2,023 | 
      | 
      | 
      | 
    - | 
      | 
      | 
      | 
    26,280 | 
      | 
 
    | Non-US sovereign debt | 
      | 
      | 
    8.54 | 
    % | 
      | 
      | 
    2,565 | 
      | 
      | 
      | 
    - | 
      | 
      | 
      | 
    - | 
      | 
      | 
      | 
    2,565 | 
      | 
 
    | Total securities sold under repurchase agreements | 
      | 
      | 
      | 
      | 
      | 
    $ | 
    136,643 | 
      | 
      | 
    $ | 
    10,984 | 
      | 
      | 
    $ | 
    7,148 | 
      | 
      | 
    $ | 
    154,775 | 
      | 
 
 
  
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