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Investment Portfolio (Details Textual) - USD ($) | Dec. 31, 2016 | Dec. 31, 2015
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Investments, Debt and Equity Securities [Abstract] |  |
Fair value of investments | $ 108,000,000 |
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |
Deferred compensation plan assets | 14,182,470 | $ 7,961,412
Trading Securities |  |
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |
Deferred compensation plan assets | 9,300,000 |
Equity Method Investments |  |
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |
Deferred compensation plan assets | 4,900,000 |
Accounting Standards Update 2015-02 [Member] | New Accounting Pronouncement, Early Adoption, Effect [Member] | Trading Securities |  |
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |
Cumulative Effect of New Accounting Principle in Period of Adoption |  | (21,100,000)
Accounting Standards Update 2015-02 [Member] | New Accounting Pronouncement, Early Adoption, Effect [Member] | Equity Method Investments |  |
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |
Cumulative Effect of New Accounting Principle in Period of Adoption |  | 21,100,000
Securities held in Consolidated Funds |  |
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |
Trading Securities | 57,355,471 | $ 0
Parent | Securities held in Consolidated Funds |  |
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |
Trading Securities | 42,600,000 |
Redeemable Noncontrolling Interest | Securities held in Consolidated Funds |  |
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |
Trading Securities | $ 14,700,000 |

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