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Debt (Summary Of Additional Information Of Credit facilities) (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019
Revolving Secured Line Of Credit [Member] |  |
Debt Instrument [Line Items] |  |
Maximum outstanding balance | $ 296.6 | $ 282.9
Average outstanding balance | 108.3 | 77.2
Warehouse Facility II [Member] |  |
Debt Instrument [Line Items] |  |
Maximum outstanding balance | 201.0 | 201.0
Average outstanding balance | 106.7 | 78.0
Warehouse Facility IV [Member] |  |
Debt Instrument [Line Items] |  |
Maximum outstanding balance | 0.0 | 100.0
Average outstanding balance | 0.0 | 1.1
Warehouse Facility V [Member] |  |
Debt Instrument [Line Items] |  |
Maximum outstanding balance | 75.0 | 35.0
Average outstanding balance | 19.1 | 0.9
Warehouse Facility VI [Member] |  |
Debt Instrument [Line Items] |  |
Maximum outstanding balance | 50.0 | 0.0
Average outstanding balance | 18.0 | 0.0
Warehouse Facility VII [Member] |  |
Debt Instrument [Line Items] |  |
Maximum outstanding balance | 125.0 | 101.5
Average outstanding balance | 61.9 | 7.1
Warehouse Facility VIII [Member] |  |
Debt Instrument [Line Items] |  |
Maximum outstanding balance | 149.0 | 145.3
Average outstanding balance | $ 28.2 | $ 7.2

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