Financial Instruments (Unrealized Gains and Losses) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Unrealized gross gains	$ 12.5	$ 20.9
Unrealized gross losses	4.0	0.5
Fair value of securities in an unrealized gain position	293.4	348.9
Fair value of securities in an unrealized loss position	$ 208.1	$ 11.4

Debt Securities, Available-for-sale, Unrealized Gain Position

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- Definition

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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- Definition

Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position without allowance for credit loss.

+ References

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