Fair Value (Details 3) (USD $) In Millions, unless otherwise specified	Jun. 30, 2011
Adjustments to pricing service valuations
Value of securities using pricing service	$ 4.7
Value of securities used in the financial statements	4.8
Indemnity | Total
Fair value by pricing source
Total available-for-sale securities and trading securities	575
Indemnity | Total | Fixed maturities
Fair value by pricing source
Total available-for-sale securities and trading securities	525
Indemnity | Total | Fixed maturities | Priced via pricing services
Fair value by pricing source
Total available-for-sale securities and trading securities	521
Indemnity | Total | Fixed maturities | Priced via market comparables/non-binding broker quote
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Indemnity | Total | Fixed maturities | Priced via internal modeling
Fair value by pricing source
Total available-for-sale securities and trading securities	4
Indemnity | Total | Preferred stock
Fair value by pricing source
Total available-for-sale securities and trading securities	20
Indemnity | Total | Preferred stock | Priced via pricing services
Fair value by pricing source
Total available-for-sale securities and trading securities	18
Indemnity | Total | Preferred stock | Priced via market comparables/non-binding broker quote
Fair value by pricing source
Total available-for-sale securities and trading securities	2
Indemnity | Total | Preferred stock | Priced via internal modeling
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Indemnity | Total | Common stock
Fair value by pricing source
Total available-for-sale securities and trading securities	30
Indemnity | Total | Common stock | Priced via pricing services
Fair value by pricing source
Total available-for-sale securities and trading securities	30
Indemnity | Total | Common stock | Priced via market comparables/non-binding broker quote
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Indemnity | Total | Common stock | Priced via internal modeling
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Exchange | Total
Fair value by pricing source
Total available-for-sale securities and trading securities	10,503
Exchange | Total | Fixed maturities
Fair value by pricing source
Total available-for-sale securities and trading securities	7,380
Exchange | Total | Fixed maturities | Priced via pricing services
Fair value by pricing source
Total available-for-sale securities and trading securities	7,232
Exchange | Total | Fixed maturities | Priced via market comparables/non-binding broker quote
Fair value by pricing source
Total available-for-sale securities and trading securities	98
Exchange | Total | Fixed maturities | Priced via internal modeling
Fair value by pricing source
Total available-for-sale securities and trading securities	50
Exchange | Total | Preferred stock
Fair value by pricing source
Total available-for-sale securities and trading securities	610
Exchange | Total | Preferred stock | Priced via pricing services
Fair value by pricing source
Total available-for-sale securities and trading securities	577
Exchange | Total | Preferred stock | Priced via market comparables/non-binding broker quote
Fair value by pricing source
Total available-for-sale securities and trading securities	33
Exchange | Total | Preferred stock | Priced via internal modeling
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Exchange | Total | Common stock
Fair value by pricing source
Total available-for-sale securities and trading securities	2,513
Exchange | Total | Common stock | Priced via pricing services
Fair value by pricing source
Total available-for-sale securities and trading securities	2,500
Exchange | Total | Common stock | Priced via market comparables/non-binding broker quote
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Exchange | Total | Common stock | Priced via internal modeling
Fair value by pricing source
Total available-for-sale securities and trading securities	13
Total
Fair value by pricing source
Total available-for-sale securities and trading securities	11,078
Indemnity | Level 1
Fair value by pricing source
Total available-for-sale securities and trading securities	39
Indemnity | Level 1 | Fixed maturities
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Indemnity | Level 1 | Fixed maturities | Priced via pricing services
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Indemnity | Level 1 | Fixed maturities | Priced via market comparables/non-binding broker quote
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Indemnity | Level 1 | Fixed maturities | Priced via internal modeling
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Indemnity | Level 1 | Preferred stock
Fair value by pricing source
Total available-for-sale securities and trading securities	9
Indemnity | Level 1 | Preferred stock | Priced via pricing services
Fair value by pricing source
Total available-for-sale securities and trading securities	9
Indemnity | Level 1 | Preferred stock | Priced via market comparables/non-binding broker quote
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Indemnity | Level 1 | Preferred stock | Priced via internal modeling
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Indemnity | Level 1 | Common stock
Fair value by pricing source
Total available-for-sale securities and trading securities	30
Indemnity | Level 1 | Common stock | Priced via pricing services
Fair value by pricing source
Total available-for-sale securities and trading securities	30
Indemnity | Level 1 | Common stock | Priced via market comparables/non-binding broker quote
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Indemnity | Level 1 | Common stock | Priced via internal modeling
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Exchange | Level 1
Fair value by pricing source
Total available-for-sale securities and trading securities	2,718
Exchange | Level 1 | Fixed maturities
Fair value by pricing source
Total available-for-sale securities and trading securities	23
Exchange | Level 1 | Fixed maturities | Priced via pricing services
Fair value by pricing source
Total available-for-sale securities and trading securities	23
Exchange | Level 1 | Fixed maturities | Priced via market comparables/non-binding broker quote
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Exchange | Level 1 | Fixed maturities | Priced via internal modeling
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Exchange | Level 1 | Preferred stock
Fair value by pricing source
Total available-for-sale securities and trading securities	195
Exchange | Level 1 | Preferred stock | Priced via pricing services
Fair value by pricing source
Total available-for-sale securities and trading securities	188
Exchange | Level 1 | Preferred stock | Priced via market comparables/non-binding broker quote
Fair value by pricing source
Total available-for-sale securities and trading securities	7
Exchange | Level 1 | Preferred stock | Priced via internal modeling
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Exchange | Level 1 | Common stock
Fair value by pricing source
Total available-for-sale securities and trading securities	2,500
Exchange | Level 1 | Common stock | Priced via pricing services
Fair value by pricing source
Total available-for-sale securities and trading securities	2,500
Exchange | Level 1 | Common stock | Priced via market comparables/non-binding broker quote
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Exchange | Level 1 | Common stock | Priced via internal modeling
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Level 1
Fair value by pricing source
Total available-for-sale securities and trading securities	2,757
Indemnity | Level 2
Fair value by pricing source
Total available-for-sale securities and trading securities	532
Indemnity | Level 2 | Fixed maturities
Fair value by pricing source
Total available-for-sale securities and trading securities	521
Indemnity | Level 2 | Fixed maturities | Priced via pricing services
Fair value by pricing source
Total available-for-sale securities and trading securities	521
Indemnity | Level 2 | Fixed maturities | Priced via market comparables/non-binding broker quote
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Indemnity | Level 2 | Fixed maturities | Priced via internal modeling
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Indemnity | Level 2 | Preferred stock
Fair value by pricing source
Total available-for-sale securities and trading securities	11
Indemnity | Level 2 | Preferred stock | Priced via pricing services
Fair value by pricing source
Total available-for-sale securities and trading securities	9
Indemnity | Level 2 | Preferred stock | Priced via market comparables/non-binding broker quote
Fair value by pricing source
Total available-for-sale securities and trading securities	2
Indemnity | Level 2 | Preferred stock | Priced via internal modeling
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Indemnity | Level 2 | Common stock
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Indemnity | Level 2 | Common stock | Priced via pricing services
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Indemnity | Level 2 | Common stock | Priced via market comparables/non-binding broker quote
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Indemnity | Level 2 | Common stock | Priced via internal modeling
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Exchange | Level 2
Fair value by pricing source
Total available-for-sale securities and trading securities	7,715
Exchange | Level 2 | Fixed maturities
Fair value by pricing source
Total available-for-sale securities and trading securities	7,307
Exchange | Level 2 | Fixed maturities | Priced via pricing services
Fair value by pricing source
Total available-for-sale securities and trading securities	7,209
Exchange | Level 2 | Fixed maturities | Priced via market comparables/non-binding broker quote
Fair value by pricing source
Total available-for-sale securities and trading securities	98
Exchange | Level 2 | Fixed maturities | Priced via internal modeling
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Exchange | Level 2 | Preferred stock
Fair value by pricing source
Total available-for-sale securities and trading securities	408
Exchange | Level 2 | Preferred stock | Priced via pricing services
Fair value by pricing source
Total available-for-sale securities and trading securities	389
Exchange | Level 2 | Preferred stock | Priced via market comparables/non-binding broker quote
Fair value by pricing source
Total available-for-sale securities and trading securities	19
Exchange | Level 2 | Preferred stock | Priced via internal modeling
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Exchange | Level 2 | Common stock
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Exchange | Level 2 | Common stock | Priced via pricing services
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Exchange | Level 2 | Common stock | Priced via market comparables/non-binding broker quote
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Exchange | Level 2 | Common stock | Priced via internal modeling
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Level 2
Fair value by pricing source
Total available-for-sale securities and trading securities	8,247
Indemnity | Level 3
Fair value by pricing source
Total available-for-sale securities and trading securities	4
Indemnity | Level 3 | Fixed maturities
Fair value by pricing source
Total available-for-sale securities and trading securities	4
Indemnity | Level 3 | Fixed maturities | Priced via pricing services
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Indemnity | Level 3 | Fixed maturities | Priced via market comparables/non-binding broker quote
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Indemnity | Level 3 | Fixed maturities | Priced via internal modeling
Fair value by pricing source
Total available-for-sale securities and trading securities	4
Indemnity | Level 3 | Common stock
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Indemnity | Level 3 | Common stock | Priced via pricing services
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Indemnity | Level 3 | Common stock | Priced via market comparables/non-binding broker quote
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Indemnity | Level 3 | Common stock | Priced via internal modeling
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Indemnity | Level 3 | Preferred stock
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Indemnity | Level 3 | Preferred stock | Priced via pricing services
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Indemnity | Level 3 | Preferred stock | Priced via market comparables/non-binding broker quote
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Indemnity | Level 3 | Preferred stock | Priced via internal modeling
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Exchange | Level 3
Fair value by pricing source
Total available-for-sale securities and trading securities	70
Exchange | Level 3 | Fixed maturities
Fair value by pricing source
Total available-for-sale securities and trading securities	50
Exchange | Level 3 | Fixed maturities | Priced via pricing services
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Exchange | Level 3 | Fixed maturities | Priced via market comparables/non-binding broker quote
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Exchange | Level 3 | Fixed maturities | Priced via internal modeling
Fair value by pricing source
Total available-for-sale securities and trading securities	50
Exchange | Level 3 | Preferred stock
Fair value by pricing source
Total available-for-sale securities and trading securities	7
Exchange | Level 3 | Preferred stock | Priced via pricing services
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Exchange | Level 3 | Preferred stock | Priced via market comparables/non-binding broker quote
Fair value by pricing source
Total available-for-sale securities and trading securities	7
Exchange | Level 3 | Preferred stock | Priced via internal modeling
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Exchange | Level 3 | Common stock
Fair value by pricing source
Total available-for-sale securities and trading securities	13
Exchange | Level 3 | Common stock | Priced via pricing services
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Exchange | Level 3 | Common stock | Priced via market comparables/non-binding broker quote
Fair value by pricing source
Total available-for-sale securities and trading securities	0
Exchange | Level 3 | Common stock | Priced via internal modeling
Fair value by pricing source
Total available-for-sale securities and trading securities	13
Level 3
Fair value by pricing source
Total available-for-sale securities and trading securities	74
Exchange
Adjustments to pricing service valuations
Number of holdings	2
Value of securities using pricing service	4.7
Value of securities used in the financial statements	$ 4.8
Fixed maturities | Priced via internal modeling
Fair value by pricing source
Number of securities	11
Common stock | Priced via internal modeling
Fair value by pricing source
Number of securities	3
Priced via internal modeling
Fair value by pricing source
Securities priced via internal modeling as a percentage of total portfolio (as a percent)	0.50%