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Condensed Consolidated Statements of Changes in Equity (Unaudited) (USD $)
In Thousands, except Share data |
Common Stock [Member]
|
Additional Paid-in Capital [Member]
|
Treasury Stock [Member]
|
Retained Earnings [Member]
|
Accumulated Other Comprehensive Income [Member]
|
Total Stockholders' Equity [Member]
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Non-controlling Interests [Member]
|
Total
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|---|---|---|---|---|---|---|---|---|
| Balance at Dec. 31, 2012 | $ 478 | $ 493,912 | $ (7,718) | $ 82,072 | $ 29,754 | $ 598,498 | $ 4,214,649 | $ 4,813,147 |
| Common stock, shares issued at Dec. 31, 2012 | 47,797,844 | |||||||
| Common stock distributed pursuant to stock plans | 22 | (22) | 5,184 | 5,184 | 5,184 | |||
| Common Stock distributed pursuant to stock plans (in shares) | 2,292,992 | |||||||
| Compensation for stock grants vesting in the future | 2,964 | 2,964 | 21,621 | 24,585 | ||||
| Dividends paid to stockholders | (9,745) | (9,745) | (9,745) | |||||
| Distributions from IBG LLC to noncontrolling interests | (70,406) | (70,406) | ||||||
| Adjustments for changes in proportionate ownership in IBG LLC | 19,826 | 19,826 | (19,826) | |||||
| Comprehensive Income | 16,935 | (7,346) | 9,589 | 122,774 | 132,363 | |||
| Balance at Jun. 30, 2013 | 500 | 516,680 | (2,534) | 89,262 | 22,408 | 626,316 | 4,268,812 | 4,895,128 |
| Common stock, shares issued at Jun. 30, 2013 | 50,090,836 | |||||||
| Balance at Dec. 31, 2013 | 548 | 583,312 | (2,492) | 98,868 | 27,028 | 707,264 | 4,384,862 | 5,092,126 |
| Common stock, shares issued at Dec. 31, 2013 | 54,788,049 | |||||||
| Common stock distributed pursuant to stock plans | 24 | (24) | 72 | 72 | 72 | |||
| Common Stock distributed pursuant to stock plans (in shares) | 2,432,410 | |||||||
| Compensation for stock grants vesting in the future | 2,966 | 2,966 | 18,635 | 21,601 | ||||
| Dividends paid to stockholders | (11,176) | (11,176) | (11,176) | |||||
| Distributions from IBG LLC to noncontrolling interests | (203,502) | (203,502) | ||||||
| Adjustments for changes in proportionate ownership in IBG LLC | 27,132 | 27,132 | (27,132) | |||||
| Comprehensive Income | 34,250 | 1,846 | 36,096 | 340,374 | 376,470 | |||
| Balance at Jun. 30, 2014 | $ 572 | $ 613,386 | $ (2,420) | $ 121,942 | $ 28,874 | $ 762,354 | $ 4,513,237 | $ 5,275,591 |
| Common stock, shares issued at Jun. 30, 2014 | 57,220,459 |