Fair Value of Financial Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Financial assets, Carrying amount:
Held-to-maturity fixed-maturity securities	$ 180,398us-gaap_HeldToMaturitySecurities	$ 220,752us-gaap_HeldToMaturitySecurities
Mortgage loans on real estate	7,182,169	6,134,525
Loans to affiliates	850,115us-gaap_DueFromRelatedParties	1,191,170us-gaap_DueFromRelatedParties
Policy loans	160,141us-gaap_LoansInsurancePolicy	158,217us-gaap_LoansInsurancePolicy
Acquired loans	201,268	205,131
Other invested assets	75,041us-gaap_OtherInvestments	50,046us-gaap_OtherInvestments
Financial liabilities, Carrying amount :
Investment contracts	84,156,386	71,735,796
Mortgage notes payable	92,184us-gaap_NotesPayable	99,210us-gaap_NotesPayable
Financial assets, Fair value:
Held-to-maturity fixed-maturity securities	204,489	219,516
Mortgage loans on real estate	7,618,106	6,554,054
Loans to affiliates	850,115	1,191,170
Policy loans	160,141us-gaap_OtherAssetsFairValueDisclosure	158,217us-gaap_OtherAssetsFairValueDisclosure
Acquired loans	273,375	247,558
Other invested assets	75,041us-gaap_InvestmentsFairValueDisclosure	50,046us-gaap_InvestmentsFairValueDisclosure
Financial liabilities, Fair value:
Investment contracts	84,921,955	72,477,568
Mortgage notes payable	109,119us-gaap_NotesPayableFairValueDisclosure	112,884us-gaap_NotesPayableFairValueDisclosure
Fair Value, Inputs, Level 2
Financial assets, Fair value:
Loans to affiliates	850,115	1,191,170
Policy loans	160,141	158,217
Acquired loans	175,888	162,320
Fair Value, Inputs, Level 3
Financial assets, Fair value:
Held-to-maturity fixed-maturity securities	204,489	219,516
Mortgage loans on real estate	7,618,106	6,554,054
Acquired loans	97,487	85,238
Other invested assets	75,041	50,046
Financial liabilities, Fair value:
Investment contracts	84,921,955	72,477,568
Mortgage notes payable	$ 109,119	$ 112,884

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Fair value at acquisition of acquired loans not accounted for as debt securities with evidence of deterioration of credit quality.

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The recorded balance, net of any applicable reductions (for example, unamortized accretable yield and allowance for loan losses). This relates to loans not accounted for debt securities with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

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Fair value of investments in debt securities classified as held-to-maturity.

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Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

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Amount of accrued obligation to policyholders that relates to insured events under individual and group annuities and supplementary insurance contracts.

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