Reinsurance - Other Reinsurance (Details) (USD $)	3 Months Ended		6 Months Ended				12 Months Ended		3 Months Ended	6 Months Ended											3 Months Ended		6 Months Ended		6 Months Ended					6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Jun. 30, 2013 Variable Annuity [Member]	Dec. 31, 2012 Variable Annuity [Member] Guaranteed Minimum Death Benefit [Member]	Jun. 30, 2013 Variable Annuity [Member] Guaranteed Minimum Death Benefit [Member]	Jun. 30, 2012 Variable Annuity [Member] Guaranteed Minimum Death Benefit [Member] Non designated [Member]	Jun. 30, 2013 Variable Annuity [Member] Guaranteed Minimum Death Benefit [Member] Non designated [Member]	Jun. 30, 2012 Variable Annuity [Member] Guaranteed Minimum Death Benefit [Member] Non designated [Member]	Jun. 30, 2013 Variable Annuity [Member] Guaranteed Minimum Income Benefit [Member]	Jun. 30, 2013 Great American Life Insurance Company [Member]	Dec. 31, 2012 Great American Life Insurance Company [Member]	Jun. 30, 2013 Prudential Retirement Insurance And Annuity Company [Member]	Dec. 31, 2012 Prudential Retirement Insurance And Annuity Company [Member]	Jun. 30, 2013 The Lincoln National Life Insurance Company And Lincoln Life And Annuity Of New York [Member]	Dec. 31, 2012 The Lincoln National Life Insurance Company And Lincoln Life And Annuity Of New York [Member]	Jun. 30, 2013 Various Reinsurers Used In The Ordinary Course Of Business [Member]	Feb. 04, 2013 Berkshire Hathway Life Insurance Company Of Nebraska [Member]	Jun. 30, 2013 Berkshire Hathway Life Insurance Company Of Nebraska [Member] Variable Annuity [Member]	Mar. 31, 2013 Berkshire Hathway Life Insurance Company Of Nebraska [Member] Variable Annuity [Member]	Jun. 30, 2013 Berkshire Hathway Life Insurance Company Of Nebraska [Member] Variable Annuity [Member]	Feb. 04, 2013 Berkshire Hathway Life Insurance Company Of Nebraska [Member] Variable Annuity [Member]	Jun. 30, 2013 Berkshire Hathway Life Insurance Company Of Nebraska [Member] Variable Annuity [Member] Guaranteed Minimum Death Benefit [Member]	Feb. 04, 2013 Berkshire Hathway Life Insurance Company Of Nebraska [Member] Variable Annuity [Member] Guaranteed Minimum Death Benefit [Member]	Jun. 30, 2013 Berkshire Hathway Life Insurance Company Of Nebraska [Member] Variable Annuity [Member] Guaranteed Minimum Income Benefit [Member] Non designated [Member]	Jun. 30, 2013 Berkshire Hathway Life Insurance Company Of Nebraska [Member] Minimum [Member] Variable Annuity [Member]	Jun. 30, 2013 Berkshire Hathway Life Insurance Company Of Nebraska [Member] Maximum [Member] Variable Annuity [Member]	Jun. 30, 2013 Berkshire Hathway Life Insurance Company Of Nebraska [Member] Other Benefits Expense [Member] Variable Annuity [Member]	Jun. 30, 2013 Berkshire Hathway Life Insurance Company Of Nebraska [Member] GMIB Fair Value (Gain) Loss [Member] Variable Annuity [Member]	Jun. 30, 2013 Berkshire Hathway Life Insurance Company Of Nebraska [Member] Other Operating Expenses [Member] Variable Annuity [Member]	Jun. 30, 2013 Other Retrocessionaires [Member] Variable Annuity [Member] Guaranteed Minimum Income Benefit [Member] Non designated [Member]	Jun. 30, 2013 Other Retrocessionaires [Member] Run-off Workers' Compensation and Personal Accident [Member]
Ceded Premiums And Fees [Abstract]
Individual life insurance and annuity business sold	$ 45,000,000	$ 46,000,000	$ 91,000,000	$ 97,000,000
Other	104,000,000	70,000,000	183,000,000	136,000,000
Total	149,000,000	116,000,000	274,000,000	233,000,000
Reinsurance Recoveries [Abstract]
Individual life insurance and annuity business sold	94,000,000	69,000,000	182,000,000	137,000,000
Other	68,000,000	42,000,000	(194,000,000)	96,000,000
Total	162,000,000	111,000,000	(12,000,000)	233,000,000
Ceded Credit Risk [Line Items]
Reinsurance recoverables	7,407,000,000		7,407,000,000		6,256,000,000			1,350,000,000					389,000,000	402,000,000	1,200,000,000	1,300,000,000	4,000,000,000	4,000,000,000	353,000,000															121,000,000
Reinsurance recoverable percent secured													100.00%		100.00%					100.00%														100.00%
Number Of Reinsurers Ongoing Operations																			85
Reserve Held For Ceded Reinsurance Recoverable Ongoing Operations																			4,000,000
Effective Exit Of Guaranteed Minimum Benefits Business [Abstract]
Pre Tax Guaranteed Benefits Reserve Strengthening							43,000,000																		700,000,000
After Tax Guaranteed Benefits Reserve Strengthening							27,000,000																		500,000,000
Ceded Reinsurance Agreement, Coverage Limit, Fixed Portion																								3,800,000,000
Ceded Reinsurance Agreement, Coverage Limit, Variable Portion																												100,000,000	300,000,000
Ceded Reinsurace Agreement, Covered Claims, Expected Amount																					4,000,000,000		4,000,000,000
Ceded Reinsurance Agreement Charge, After-tax																							507,000,000
Ceded Reinsurance Agreement Charge, Pre-tax																							781,000,000							727,000,000	45,000,000	9,000,000
Ceded Reinsurance Agreement, Premium Amount																										1,647,000,000
Reinsurance preimums paid			2,196,000,000	0																	700,000,000	1,500,000,000
Reinsurance premiums due																								2,200,000,000
Ceded Reinsurance Agreement, Cost Of Reinsurance																					700,000,000		700,000,000
Derivative Gain (Loss)									28,000,000	(32,000,000)	(59,000,000)
GMIB assets												950,000,000															400,000,000						500,000,000
Combined GMDB recoverables and GMIB assets						$ 2,300,000,000															$ 1,700,000,000		$ 1,700,000,000
Combined GMDB recoverables and GMIB assets percent secured						85.00%