v2.4.0.8

Equity And Earnings Per Share (Narrative) (Details) (USD $) | 3 Months Ended | 6 Months Ended | 12 Months Ended | 36 Months Ended | 86 Months Ended |
--- | --- | --- | --- | --- | --- | ---
Jun. 30, 2014 | Mar. 31, 2014 | Jun. 30, 2014 | Jun. 30, 2013 | Dec. 31, 2013 | Dec. 31, 2011 | Dec. 31, 2010 | Jun. 30, 2014 | Jun. 30, 2014 | May 03, 2007
Equity And Earnings Per Share [Line Items] |  |  |  |  |  |  |  |  |  |
IBG Inc. ownership % of IBG LLC | 14.10% |  | 14.10% |  |  |  |  | 14.10% | 14.10% | 10.00%
IBG Holdings ownership % of IBG LLC | 85.90% |  | 85.90% |  |  |  |  | 85.90% | 85.90% | 90.00%
IBG Holdings Redemption of IBG LLC |  |  |  |  |  |  |  |  |  | 10.00%
IBG Holdings LLC Ownership Percentage of Class B Common Stock |  |  |  |  |  |  |  |  |  | 100.00%
Common stock, par value | $ 0.01 |  | $ 0.01 |  | $ 0.01 |  |  | $ 0.01 | $ 0.01 |
Preferred stock shares authorized | 10,000 |  | 10,000 |  | 10,000 |  |  | 10,000 | 10,000 |
Preferred stock shares issued | 0 |  | 0 |  | 0 |  |  | 0 | 0 |
Preferred stock shares outstanding | 0 |  | 0 |  | 0 |  |  | 0 | 0 |
Unamortized deferred tax asset arising from equity offerings | $ 283,500,000 |  | $ 283,500,000 |  | $ 294,700,000 |  |  | $ 283,500,000 | $ 283,500,000 |
Deferred tax asset arising from equity offerings | 420,400,000 |  | 420,400,000 |  |  |  |  | 420,400,000 | 420,400,000 |
Percent of Tax Savings Owed to IBG Holdings LLC |  |  | 85.00% |  |  |  |  |  |  |
Percentage of tax savings retained by IBG Inc. |  |  | 15.00% |  |  |  |  |  |  |
Tax savings owed to IBG Holdings LLC | 357,400,000 |  | 357,400,000 |  |  |  |  | 357,400,000 | 357,400,000 |
Tax savings retained by IBG Inc. | 63,100,000 |  | 63,100,000 |  |  |  |  | 63,100,000 | 63,100,000 |
Tax savings paid to IBG Holdings LLC |  |  | 15,700,000 |  |  |  |  |  | 86,200,000 |
Exchange Agreement Future Redemption Schedule |  |  |  |  |  |  |  | 12.5% annually for seven (7) years and 2.5% in the eighth year. |  |
Shares reserved for future issuance |  |  |  |  |  |  |  |  |  | 360,000,000
Shares redeemed by IBG Holdings from IBG LLC |  |  |  |  |  |  | 5,013,259 |  |  |
Cash Redemptions IBG Holdings |  |  |  |  |  |  | 114,000,000 |  |  |
Shares Issued |  |  |  |  | 4,683,415 | 1,983,624 |  |  |  |
Thomas Peterffy and Affiliates Ownership | 87.60% |  | 87.60% |  |  |  |  | 87.60% | 87.60% | 84.60%
Dividends paid by IBG LLC |  |  | 235,800,000 |  |  |  |  |  |  |
Cash dividend paid to IBG, Inc. |  |  | 32,300,000 |  |  |  |  |  |  |
Dividends paid to common shareholders | $ 5,700,000 | $ 5,500,000 | $ 11,176,000 | $ 9,745,000 |  |  |  |  |  |
Declaration Date |  |  | Jul. 15, 2014 |  |  |  |  |  |  |
Dividend per share | $ 0.10 | $ 0.10 | $ 0.10 |  |  |  |  |  |  |
Payment Date |  |  | Sep. 12, 2014 |  |  |  |  |  |  |
Record Date |  |  | Aug. 29, 2014 |  |  |  |  |  |  |
Common Class A |  |  |  |  |  |  |  |  |  |
Equity And Earnings Per Share [Line Items] |  |  |  |  |  |  |  |  |  |
Shares authorized | 1,000,000,000 |  | 1,000,000,000 |  | 1,000,000,000 |  |  | 1,000,000,000 | 1,000,000,000 |
Common stock, shares issued | 57,220,459 |  | 57,220,459 |  | 54,788,049 |  |  | 57,220,459 | 57,220,459 |
Common stock, shares outstanding | 57,098,889 |  | 57,098,889 |  | 54,664,095 |  |  | 57,098,889 | 57,098,889 |
Common Class B |  |  |  |  |  |  |  |  |  |
Equity And Earnings Per Share [Line Items] |  |  |  |  |  |  |  |  |  |
Shares authorized | 100 |  | 100 |  | 100 |  |  | 100 | 100 |
Common stock, shares issued | 100 |  | 100 |  | 100 |  |  | 100 | 100 |
Common stock, shares outstanding | 100 |  | 100 |  | 100 |  |  | 100 | 100 |

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