Basis of Presentation Adoption of Recent Accounting Pronouncements (Details) $ in Millions	Jan. 01, 2018 USD ($)
Adoption of Recent Accounting Pronouncements [Abstract]
Unrealized gains on equity securities reclassified from accumulated other comprehensive income to retained earnings, after tax upon adoption of ASU 2016-01	$ 60.8
Stranded income tax effects resulting from TCJA reclassified from accumulated other comprehensive income to retained earnings upon adoption of ASU 2018-02	$ 4.0

Unrealized gains on equity securities reclassified from accumulated other comprehensive income to retained earnings, after tax upon adoption of ASU 2016-01

No definition available.

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Balance Type:	credit
Period Type:	duration