Reinsurance - Other Reinsurance (Details) (USD $)	3 Months Ended		9 Months Ended					12 Months Ended	3 Months Ended	9 Months Ended											3 Months Ended			9 Months Ended					3 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Sep. 30, 2013 Guaranteed Minimum Death Benefit [Member]	Sep. 30, 2013 Variable Annuity [Member]	Dec. 31, 2012 Variable Annuity [Member] Guaranteed Minimum Death Benefit [Member]	Sep. 30, 2012 Variable Annuity [Member] Guaranteed Minimum Death Benefit [Member] Non designated [Member]	Sep. 30, 2013 Variable Annuity [Member] Guaranteed Minimum Death Benefit [Member] Non designated [Member]	Sep. 30, 2012 Variable Annuity [Member] Guaranteed Minimum Death Benefit [Member] Non designated [Member]	Sep. 30, 2013 Variable Annuity [Member] Guaranteed Minimum Income Benefit [Member]	Sep. 30, 2013 Great American Life Insurance Company [Member]	Dec. 31, 2012 Great American Life Insurance Company [Member]	Sep. 30, 2013 Prudential Retirement Insurance And Annuity Company [Member]	Dec. 31, 2012 Prudential Retirement Insurance And Annuity Company [Member]	Sep. 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]	Sep. 30, 2013 Various Reinsurers Used In The Ordinary Course Of Business [Member]	Feb. 04, 2013 Berkshire Hathway Life Insurance Company Of Nebraska [Member]	Mar. 31, 2013 Berkshire Hathway Life Insurance Company Of Nebraska [Member] Variable Annuity [Member]	Sep. 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]	Sep. 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]	Sep. 30, 2013 Berkshire Hathway Life Insurance Company Of Nebraska [Member] Variable Annuity [Member] Guaranteed Minimum Income Benefit [Member] Non designated [Member]	Sep. 30, 2013 Berkshire Hathway Life Insurance Company Of Nebraska [Member] Minimum [Member] Variable Annuity [Member]	Sep. 30, 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]	Sep. 30, 2013 Other Retrocessionaires [Member] Variable Annuity [Member] Guaranteed Minimum Income Benefit [Member] Non designated [Member]	Sep. 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	$ 39,000,000	$ 41,000,000	$ 130,000,000	$ 138,000,000
Other	90,000,000	72,000,000	273,000,000	208,000,000
Total	129,000,000	113,000,000	403,000,000	346,000,000
Reinsurance Recoveries [Abstract]
Individual life insurance and annuity business sold	74,000,000	79,000,000	256,000,000	216,000,000
Other	125,000,000	54,000,000	(69,000,000)	150,000,000
Total	199,000,000	133,000,000	187,000,000	366,000,000
Ceded Credit Risk [Line Items]
Reinsurance recoverables	7,371,000,000		7,371,000,000		6,256,000,000	1,400,000,000							380,000,000	402,000,000	1,200,000,000	1,300,000,000	3,900,000,000	4,000,000,000	351,000,000														118,000,000
Reinsurance recoverable percent secured													96.00%		100.00%					100.00%													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			2,196,000,000	0																	1,500,000,000			1,647,000,000
Reinsurance premiums due																							2,200,000,000
Ceded Reinsurance Agreement, Cost Of Reinsurance																						700,000,000
Derivative Gain (Loss)									(35,000,000)	(32,000,000)	(94,000,000)
GMIB assets												850,000,000														400,000,000						500,000,000
Combined GMDB recoverables and GMIB assets							$ 2,200,000,000															$ 1,700,000,000
Combined GMDB recoverables and GMIB assets percent secured							86.00%