Variable Interest Entities (Narrative) (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Variable Interest Entities [Abstract] | |||
| Voluntary repurchases and substitutions | $ 9.5 | $ 6.5 | $ 3.3 |
| X | ||||||||||
- Definition Voluntary repurchases and substitutions. No definition available.
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| X | ||||||||||
- References No definition available.
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