Offsetting of Derivative Assets And Liabilities (Detail) - USD ($) $ in Thousands		Mar. 31, 2017	Dec. 31, 2016
Assets
Gross estimated fair value of derivatives		$ 21,543	$ 39,022
Estimated fair value of derivatives presented on the Balance Sheets		2,609	16,526
Net amount after application of master netting agreements and collateral		52	1,304
Liabilities
Gross estimated fair value of derivatives		26,031	37,309
Estimated fair value of derivatives presented on the Balance Sheets		7,051	15,165
Net amount after application of master netting agreements and collateral		1,959	916
OTC - Bilateral
Assets
Gross estimated fair value of derivatives		19,735	37,344
Amounts offset on the balance sheets	[1]	(13,743)	(18,014)
Cash collateral	[2],[3]	(3,383)	(2,804)
Gross Amounts Not Offset in the Balance Sheet, Financial Instruments	[4]	(2,557)	(15,222)
Liabilities
Gross estimated fair value of derivatives		20,794	32,832
Amounts offset on the balance sheet	[1]	(13,743)	(18,014)
Gross Amounts Not Offset in the Balance Sheet, Financial Instruments	[4]	(5,092)	(14,249)
OTC - Cleared
Assets
Gross estimated fair value of derivatives		1,808	1,678
Amounts offset on the balance sheets	[1]	(1,808)	(1,678)
Liabilities
Gross estimated fair value of derivatives		5,237	4,477
Amounts offset on the balance sheet	[1]	(1,808)	(1,678)
Cash collateral	[2],[3]	$ (3,429)	$ (2,452)

[1] Estimated fair value of derivatives is limited to the amount that is subject to set-off

[2] The amount of cash collateral offset in the table above is limited to the net estimated fair value of derivatives after application of netting agreements. Cash collateral received for over-the-counter ("OTC") OTC-Bilateral and OTC-Cleared derivatives is included in cash and cash equivalents, short-term investments, or fixed maturity securities, and the obligation to return it, beyond what is already being setoff, is included in payables for collateral under securities loaned, reverse repurchase agreements and derivatives. At March 31, 2017, the Company received $537 of excess cash collateral. The Company had no excess cash collateral received from counterparties at December 31, 2016

[3] The receivable for the return of cash collateral provided to the counterparty, beyond what is being setoff, is included in other assets. The amount reported in the table above does not include initial margin on Exchange-Traded and OTC-Cleared derivatives. At March 31, 2017, the Company provided excess cash collateral of $178, which is not included in the table above due to the foregoing limitation. At December 31, 2016, the Company had no excess cash collateral provided to counterparties.

[4] Securities collateral received or pledged by the Company is held in separate custodial accounts and is not recorded on the Balance Sheets. The amount of securities collateral offset in the table above is limited to the net estimated fair value of derivatives after application of netting agreements and cash collateral. At March 31, 2017 and December 31, 2016, the Company received excess securities collateral with an estimated fair value of $2,320 and $395, respectively, for its OTC-Bilateral derivatives, which are not included in the table above due to the foregoing limitation. At March 31, 2017 and December 31, 2016, the Company provided excess securities collateral with an estimated fair value of $1,730 and $1,878, respectively, for its OTC-Bilateral derivatives, which are not included in the table above due to the foregoing limitation. At March 31, 2017 and December 31, 2016, the Company also provided securities initial margin with an estimated fair value of $11,324 and $11,291, respectively, for its OTC-Cleared derivatives, which are not included in the table above.