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Derivative And Hedging Instruments (Schedule Of Terms Of Interest Rate Cap Agreements) (Details) - USD ($) $ in Millions | Dec. 31, 2017 | Dec. 31, 2016
--- | --- | ---
Derivative [Line Items] |  |  |  |
Debt financing amount |  | $ 3,093.0 |  | $ 2,622.1
Interest rate swap fair value |  | 0.0 |  | 0.0
Warehouse Facility II [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Debt financing amount |  | 400.0 | [1],[2] | 400.0
Warehouse Facility II [Member] | 5.50% Cap Interest Rate [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional value |  | $ 205.0 |  | $ 325.0
Cap Interest Rate | [3] | 5.50% |  | 5.50%
Warehouse Facility IV [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Debt financing amount |  | $ 100.0 | [1],[2] | $ 75.0
Notional value |  | 100.0 |  | 75.0
Warehouse Facility IV [Member] | 5.50% Cap Interest Rate [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional value |  | $ 75.0 |  |
Cap Interest Rate | [3] | 5.50% |  |
Warehouse Facility IV [Member] | Original 5.50% Cap Interest Rate [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional value |  |  |  | $ 18.8
Cap Interest Rate | [3] |  |  | 5.50%
Warehouse Facility IV [Member] | Additional 5.50% Cap Interest Rate [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional value |  |  |  | $ 56.2
Cap Interest Rate | [3] |  |  | 5.50%
Warehouse Facility IV [Member] | 6.50% Cap Interest Rate [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional value |  | $ 25.0 |  |
Cap Interest Rate | [3] | 6.50% |  |
Warehouse Facility V [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Debt financing amount |  | $ 100.0 | [1],[2] | $ 100.0
Warehouse Facility V [Member] | 5.50% Cap Interest Rate [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional value |  | $ 75.0 |  | $ 75.0
Cap Interest Rate | [3] | 5.50% |  | 5.50%
Term ABS 2016-1 [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Debt financing amount |  | $ 385.0 | [1] | $ 385.0
Term ABS 2016-1 [Member] | 5.00% Cap Interest Rate [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional value |  | $ 385.0 |  | $ 385.0
Cap Interest Rate | [3] | 5.00% |  | 5.00%
Warehouse Facility VII [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Debt financing amount | [1],[2] | $ 150.0 |  |
Warehouse Facility VII [Member] | 5.50% Cap Interest Rate [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Notional value |  | $ 150.0 |  |
Cap Interest Rate | [3] | 5.50% |  |
[1] | Financing made available only to a specified subsidiary of the Company.
[2] | Interest rate cap agreements are in place to limit the exposure to increasing interest rates.
[3] | Rate excludes the spread over the LIBOR rate.

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