SCHEDULE I SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	$ 11,171
Estimated fair value	12,074
Amount at which shown in the balance sheet	12,074
Indemnity
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	768
Estimated fair value	809
Amount at which shown in the balance sheet	809
Indemnity | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	559
Estimated fair value	573
Amount at which shown in the balance sheet	573
Indemnity | Trading securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	23
Estimated fair value	27
Amount at which shown in the balance sheet	27
Indemnity | States & political subdivisions | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	208
Estimated fair value	221
Amount at which shown in the balance sheet	221
Indemnity | Corporate debt securities | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	303
Estimated fair value	303
Amount at which shown in the balance sheet	303
Indemnity | Commercial mortgage-backed securities (CMBS) | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	13
Estimated fair value	13
Amount at which shown in the balance sheet	13
Indemnity | Collateralized debt obligations (CDO) | Available-for-sale securities
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
Indemnity | Other debt securities | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	7
Estimated fair value	7
Amount at which shown in the balance sheet	7
Indemnity | Fixed maturities | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	535
Estimated fair value	548
Amount at which shown in the balance sheet	548
Indemnity | Nonredeemable preferred stock | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	24
Estimated fair value	25
Amount at which shown in the balance sheet	25
Indemnity | Limited partnerships
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	185
Estimated fair value	208
Amount at which shown in the balance sheet	208
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	10,403
Estimated fair value	11,265
Amount at which shown in the balance sheet	11,265
Exchange | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	7,360
Estimated fair value	7,856
Amount at which shown in the balance sheet	7,856
Exchange | Trading securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	2,021
Estimated fair value	2,308
Amount at which shown in the balance sheet	2,308
Exchange | U.S. government & agencies | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	16
Estimated fair value	17
Amount at which shown in the balance sheet	17
Exchange | States & political subdivisions | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	1,289
Estimated fair value	1,379
Amount at which shown in the balance sheet	1,379
Exchange | Foreign government securities | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	15
Estimated fair value	15
Amount at which shown in the balance sheet	15
Exchange | Corporate debt securities | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	5,144
Estimated fair value	5,499
Amount at which shown in the balance sheet	5,499
Exchange | Residential mortgage-backed securities (RMBS) | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	178
Estimated fair value	189
Amount at which shown in the balance sheet	189
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	66
Amount at which shown in the balance sheet	66
Exchange | Collateralized debt obligations (CDO) | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	66
Estimated fair value	65
Amount at which shown in the balance sheet	65
Exchange | Other debt securities | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	59
Estimated fair value	62
Amount at which shown in the balance sheet	62
Exchange | Fixed maturities | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	6,829
Estimated fair value	7,292
Amount at which shown in the balance sheet	7,292
Exchange | Nonredeemable preferred stock | Available-for-sale securities
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	531
Estimated fair value	564
Amount at which shown in the balance sheet	564
Exchange | Limited partnerships
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	1,003
Estimated fair value	1,082
Amount at which shown in the balance sheet	1,082
Exchange | Life policy loans
SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES
Amortized cost	15
Estimated fair value	15
Amount at which shown in the balance sheet	15
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