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Percentage of voting equity interests acquired at the acquisition date in the business combination.

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In a business combination in which the amount of net identifiable assets acquired and liabilities assumed exceeds the aggregate consideration transferred or to be transferred (as defined), this element represents the amount of gain recognized by the entity.

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Amount of increase in assets, excluding financial assets, lacking physical substance with a definite life, from an acquisition.

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Amount of increase in assets, excluding financial assets and goodwill, lacking physical substance with an indefinite life, from an acquisition.

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Goodwill and Intangible Assets - Narrative Disclosures (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Claims Analytics Inc.
Goodwill And Intangible Assets [Line Items]
Percentage of voting interests acquired	100.00%
Claims Analytics Inc. \| Customer relationships
Goodwill And Intangible Assets [Line Items]
Definite-lived intangible assets acquired during the year	$ 4
Aurigen Capital Limited
Goodwill And Intangible Assets [Line Items]
Business Combination, Bargain Purchase, Gain Recognized, Amount		$ 1
Aurigen Capital Limited \| Life VOBA
Goodwill And Intangible Assets [Line Items]
Definite-lived intangible assets acquired during the year		76
Aurigen Capital Limited \| Insurance licenses
Goodwill And Intangible Assets [Line Items]
Indefinite-lived intangible assets acquired during the year		$ 2