Condensed Financial Information of Parent Company - Statements of Income (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues
Investment Income									$ 1,394	$ 1,465	$ 1,556
Other Revenues									7	14	8
Realized Investment Gains (Losses), Net									369	402	193
TOTAL REVENUES	3,476	3,574	3,542	3,506	3,476	3,403	3,551	3,517	14,098	13,947	13,595
Expenses
Corporate Expenses									249	254	270
Investment Expenses									42	49	38
Other Expenses									16	22	11
Federal and Foreign Income Tax	204	224	179	154	217	198	217	260	761	892	451
NET INCOME	558	594	499	449	569	541	579	656	2,100	2,345	1,545
Other Comprehensive Income (Loss), Net of Tax									75	(396)	236
COMPREHENSIVE INCOME									2,175	1,949	1,781
Parent Company [Member]
Revenues
Investment Income									26	29	38
Other Revenues										6
Realized Investment Gains (Losses), Net									4	99	(6)
TOTAL REVENUES									30	134	32
Expenses
Corporate Expenses									249	262	268
Investment Expenses									3	4	2
Other Expenses									3	8
TOTAL EXPENSES									255	274	270
Loss before Federal and Foreign Income Tax and Equity in Net Income of Consolidated Subsidiaries									(225)	(140)	(238)
Federal and Foreign Income Tax									1		4
Loss before Equity in Net Income of Consolidated Subsidiaries									(226)	(140)	(242)
Equity in Net Income of Consolidated Subsidiaries									2,326	2,485	1,787
NET INCOME									2,100	2,345	1,545
Other Comprehensive Income (Loss), Net of Tax									75	(396)	236
COMPREHENSIVE INCOME									$ 2,175	$ 1,949	$ 1,781