Invested Assets and Related Income - Fair Value and Amortized Cost of Tax Exempt Fixed Maturities Other Than Pre-Refunded Bonds (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Texas [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	$ 1,990	$ 2,361
Amortized Cost	1,904	2,171
New York [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	1,839	1,603
Amortized Cost	1,809	1,487
California [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	1,139	1,189
Amortized Cost	1,093	1,089
Illinois [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	1,116	1,260
Amortized Cost	1,094	1,161
Florida [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	903	912
Amortized Cost	877	844
Special Revenue Bonds [Member] | Texas [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	930	1,041
Special Revenue Bonds [Member] | New York [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	1,611	1,401
Special Revenue Bonds [Member] | California [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	859	888
Special Revenue Bonds [Member] | Illinois [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	577	683
Special Revenue Bonds [Member] | Florida [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	757	771
Municipal and Political Subdivision General Obligation Bonds [Member] | Texas [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	830	1,053
Municipal and Political Subdivision General Obligation Bonds [Member] | New York [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	197	169
Municipal and Political Subdivision General Obligation Bonds [Member] | California [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	82	107
Municipal and Political Subdivision General Obligation Bonds [Member] | Illinois [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	483	518
Municipal and Political Subdivision General Obligation Bonds [Member] | Florida [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	38	27
State General Obligation Bonds [Member] | Texas [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	230	267
State General Obligation Bonds [Member] | New York [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	31	33
State General Obligation Bonds [Member] | California [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	198	194
State General Obligation Bonds [Member] | Illinois [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	56	59
State General Obligation Bonds [Member] | Florida [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	$ 108	$ 114