Segment and Geographical Information - Summary of Assets and Profit or Loss by Segment (Parenthetical) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Investment and Savings Products Segment [Member]
Segment Reporting Information [Line Items]
Assets, excluding separate account assets	$ 112.0	$ 103.7	$ 93.8

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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