Investments - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	0 Months Ended
	Jun. 30, 2014	Jun. 30, 2014	Dec. 31, 2013
Investments Debt And Equity Securities [Abstract]
Net unrealized gains on investments included in AOCI		$ 841	$ 478
Additional other than temporary impairment losses	0
Future capital call commitments		348
Commitments to purchase various privately placed debt securities, including bank loans		244
Commitments to sell various privately placed debt securities, including bank loans		$ 158