Equity - Capital Requirements (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Equity [Abstract]
Capital Required for Capital Adequacy	$ 545.0	$ 520.3
Capital	727.6	657.1
Excess Capital	$ 182.6	$ 136.8

The amount of total capital as defined in the regulations.

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