Fair Value Measurements - Measured Under Certain Conditions (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2016	Mar. 31, 2015
Financing Receivable, Impaired [Line Items]
Realized investment losses on impaired commercial mortgage loans and real estate entities	$ 0	$ 4
Maximum [Member]
Financing Receivable, Impaired [Line Items]
Impaired commercial mortgage loans and real estate entities as a percent of total investments		1.00%

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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