SCHEDULE I SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	$ 11,373
Estimated fair value	12,814
Amount at which shown in the balance sheet	12,814
Indemnity
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	643
Estimated fair value	688
Amount at which shown in the balance sheet	688
Indemnity | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	491
Estimated fair value	507
Amount at which shown in the balance sheet	507
Indemnity | States & political subdivisions | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	172
Estimated fair value	185
Amount at which shown in the balance sheet	185
Indemnity | Corporate debt securities | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	259
Estimated fair value	261
Amount at which shown in the balance sheet	261
Indemnity | Commercial mortgage-backed securities (CMBS) | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	3
Estimated fair value	3
Amount at which shown in the balance sheet	3
Indemnity | Collateralized debt obligations (CDO) | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	3
Estimated fair value	3
Amount at which shown in the balance sheet	3
Indemnity | Fixed maturities | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	437
Estimated fair value	452
Amount at which shown in the balance sheet	452
Indemnity | Nonredeemable preferred stock | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	28
Estimated fair value	29
Amount at which shown in the balance sheet	29
Indemnity | Common stock | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	26
Estimated fair value	26
Amount at which shown in the balance sheet	26
Indemnity | Limited partnerships
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	151
Estimated fair value	180
Amount at which shown in the balance sheet	180
Indemnity | Real estate mortgage loans
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	1
Estimated fair value	1
Amount at which shown in the balance sheet	1
Exchange
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	10,730
Estimated fair value	12,126
Amount at which shown in the balance sheet	12,126
Exchange | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	7,887
Estimated fair value	8,652
Amount at which shown in the balance sheet	8,652
Exchange | Trading securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	1,910
Estimated fair value	2,417
Amount at which shown in the balance sheet	2,417
Exchange | U.S. government & agencies | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	190
Estimated fair value	191
Amount at which shown in the balance sheet	191
Exchange | States & political subdivisions | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	1,218
Estimated fair value	1,321
Amount at which shown in the balance sheet	1,321
Exchange | Foreign government securities | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	15
Estimated fair value	16
Amount at which shown in the balance sheet	16
Exchange | Corporate debt securities | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	5,211
Estimated fair value	5,777
Amount at which shown in the balance sheet	5,777
Exchange | Residential mortgage-backed securities (RMBS) | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	226
Estimated fair value	231
Amount at which shown in the balance sheet	231
Exchange | Commercial mortgage-backed securities (CMBS) | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	62
Estimated fair value	67
Amount at which shown in the balance sheet	67
Exchange | Collateralized debt obligations (CDO) | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	43
Estimated fair value	49
Amount at which shown in the balance sheet	49
Exchange | Other debt securities | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	51
Estimated fair value	55
Amount at which shown in the balance sheet	55
Exchange | Fixed maturities | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	7,016
Estimated fair value	7,707
Amount at which shown in the balance sheet	7,707
Exchange | Nonredeemable preferred stock | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	555
Estimated fair value	631
Amount at which shown in the balance sheet	631
Exchange | Common stock | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	316
Estimated fair value	314
Amount at which shown in the balance sheet	314
Exchange | Limited partnerships
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	913
Estimated fair value	1,037
Amount at which shown in the balance sheet	1,037
Exchange | Life policy loans
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	16
Estimated fair value	16
Amount at which shown in the balance sheet	16
Exchange | Real estate mortgage loans
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	4
Estimated fair value	4
Amount at which shown in the balance sheet	$ 4