Schedule of Non-Recourse Funding Obligations of Special Purpose Consolidated Captive Insurance Subsidiaries (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Nonrecourse Funding Obligations [Line Items]
Non-recourse funding obligations	$ 2,038		$ 2,066
River Lake Insurance Company (a), Due 2033
Nonrecourse Funding Obligations [Line Items]
Non-recourse funding obligations	570	[1]	570	[1]
River Lake Insurance Company (b), Due 2033
Nonrecourse Funding Obligations [Line Items]
Non-recourse funding obligations	461	[2]	489	[2]
River Lake Insurance Company II (a), Due 2035
Nonrecourse Funding Obligations [Line Items]
Non-recourse funding obligations	192	[1]	192	[1]
River Lake Insurance Company II (b), Due 2035
Nonrecourse Funding Obligations [Line Items]
Non-recourse funding obligations	500	[2]	500	[2]
Rivermount Insurance Company I (a), Due 2050
Nonrecourse Funding Obligations [Line Items]
Non-recourse funding obligations	$ 315	[1]	$ 315	[1]

[1] Accrual of interest based on one-month LIBOR that resets every 28 days plus a fixed margin.

[2] Accrual of interest based on one-month LIBOR that resets on a specified date each month plus a contractual margin.