Reinsurance - Other Reinsurance (Details) (USD $)	3 Months Ended					12 Months Ended	3 Months Ended												0 Months Ended	3 Months Ended		3 Months Ended					3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Mar. 31, 2013 Guaranteed Minimum Death Benefit [Member]	Mar. 31, 2013 Guaranteed Minimum Income Benefit [Member]	Dec. 31, 2012 Variable Annuity [Member] Guaranteed Minimum Death Benefit [Member]	Mar. 31, 2013 Variable Annuity [Member] Guaranteed Minimum Death Benefit [Member] Non designated [Member]	Mar. 31, 2012 Variable Annuity [Member] Guaranteed Minimum Death Benefit [Member] Non designated [Member]	Mar. 31, 2013 Great American Life Insurance Company [Member]	Dec. 31, 2012 Great American Life Insurance Company [Member]	Mar. 31, 2013 Prudential Retirement Insurance And Annuity Company [Member]	Dec. 31, 2012 Prudential Retirement Insurance And Annuity Company [Member]	Mar. 31, 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]	Mar. 31, 2013 Various Reinsurers Used In The Ordinary Course Of Business [Member]	Mar. 31, 2013 Enstar Group Limited [Member]	Mar. 31, 2013 Berkshire Hathway Life Insurance Company Of Nebraska [Member]	Feb. 04, 2013 Berkshire Hathway Life Insurance Company Of Nebraska [Member]	Apr. 18, 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]	Feb. 04, 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] Guaranteed Minimum Death Benefit [Member]	Feb. 04, 2013 Berkshire Hathway Life Insurance Company Of Nebraska [Member] Variable Annuity [Member] Guaranteed Minimum Death Benefit [Member]	Mar. 31, 2013 Berkshire Hathway Life Insurance Company Of Nebraska [Member] Variable Annuity [Member] Guaranteed Minimum Income Benefit [Member] Non designated [Member]	Mar. 31, 2013 Berkshire Hathway Life Insurance Company Of Nebraska [Member] Minimum [Member] Variable Annuity [Member]	Mar. 31, 2013 Berkshire Hathway Life Insurance Company Of Nebraska [Member] Maximum [Member] Variable Annuity [Member]	Mar. 31, 2013 Berkshire Hathway Life Insurance Company Of Nebraska [Member] Other Benefits Expense [Member] Variable Annuity [Member]	Mar. 31, 2013 Berkshire Hathway Life Insurance Company Of Nebraska [Member] GMIB Fair Value (Gain) Loss [Member] Variable Annuity [Member]	Mar. 31, 2013 Berkshire Hathway Life Insurance Company Of Nebraska [Member] Other Operating Expenses [Member] Variable Annuity [Member]	Mar. 31, 2013 Other Retrocessionaires [Member] Variable Annuity [Member] Guaranteed Minimum Income Benefit [Member] Non designated [Member]
Ceded Premiums And Fees [Abstract]
Individual life insurance and annuity business sold	$ 46,000,000	$ 51,000,000
Other	79,000,000	66,000,000
Total	125,000,000	117,000,000
Reinsurance Recoveries [Abstract]
Individual life insurance and annuity business sold	88,000,000	68,000,000
Other	(262,000,000)	54,000,000
Total	(174,000,000)	122,000,000
Ceded Credit Risk [Line Items]
Reinsurance recoverables	7,514,000,000		6,256,000,000	1,400,000,000	1,100,000,000				394,000,000	402,000,000	1,300,000,000	1,300,000,000	4,000,000,000	4,000,000,000	346,000,000	125,000,000				1,800,000,000
Reinsurance recoverable percent secured									100.00%		100.00%					99.00%		100.00%
Number Of Reinsurers Ongoing Operations															80
Reserve Held For Ceded Reinsurance Recoverable Ongoing Operations															3,000,000
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
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	1,475,000,000	0																	700,000,000	1,500,000,000
Reinsurance premiums due																			0	700,000,000	2,200,000,000
Ceded Reinsurance Agreement, Cost Of Reinsurance																				700,000,000
Derivative Gain Loss							(32,000,000)	(87,000,000)
GMIB assets																								500,000,000						600,000,000
Combined GMDB recoverables and GMIB assets	$ 2,500,000,000																$ 1,800,000,000
Combined GMDB recoverables and GMIB assets percent secured	80.00%