Summary of Investments - SOI Ltd partnership Sec lending Special deposits (Details 5) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2015	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Limited partnership and other corporation interests	$ 45,197	$ 49,421
Interest in various upper-tier LIHLPs (as a percent)	99.00%
Nature and activities of the VIEs and the effect on financial statements
Carrying value in relation to the activities of the VIEs	$ 5,152	7,464
Maximum exposure to loss in relation to the activities of the VIEs	5,152	7,464
Special deposits and securities lending
Fair value of securities on deposit with governmental authorities	14,237	14,612
Securities loaned to third parties at amortized cost	186,082	15,252
Estimated fair value of securities loaned to third parties	184,965	15,423
Restricted cash received as collateral	88,660	13,741
Securities received as collateral	103,103	$ 2,131
Transfer of certain financial assets accounted for as secured borrowings
Securities lending transactions	184,965
Fixed Maturities [Member]
Transfer of certain financial assets accounted for as secured borrowings
Securities lending transactions	184,965
Maturity Overnight and Continuous \| U.S. government direct obligations and U.S. agencies
Transfer of certain financial assets accounted for as secured borrowings
Securities lending transactions	13,021
Maturity Overnight and Continuous \| Corporate debt securities
Transfer of certain financial assets accounted for as secured borrowings
Securities lending transactions	$ 171,944

Fair value of securities loaned to other entities.

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Amount of cash subject to withdrawal restrictions, restricted deposits held as compensating balances, and cash and securities segregated in compliance with regulations (such as cash deposited in a special reserve account for the exclusive benefit of customers).

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The amount of cash received as security in return for loaning securities to another party.

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Total investments in (A) an entity in which the entity has significant influence, but does not have control, (B) subsidiaries that are not required to be consolidated and are accounted for using the equity and or cost method, and (C) an entity in which the reporting entity shares control of the entity with another party or group. Includes long-term advances receivable from a party that is affiliated with the reporting entity by means of direct or indirect ownership.

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The number of units or percentage investment held by one or more members or limited partners of the LLC or LP.

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Amount, after the effects of master netting arrangements, of securities loaned to entities in exchange for collateral. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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The carrying amount of the consolidated Variable Interest Entity's assets included in the reporting entity's statement of financial position.

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The reporting entity's maximum amount of exposure to loss as a result of its involvement with the Variable Interest Entity (VIE).

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