Pension and Postretirement Plans (Narrative) (Details) (USD $)	9 Months Ended			3 Months Ended		9 Months Ended		3 Months Ended			9 Months Ended		9 Months Ended				9 Months Ended
	Sep. 30, 2012	Oct. 02, 2011	Dec. 31, 2011	Sep. 30, 2012 Pension Plans [Member] companies	Oct. 02, 2011 Pension Plans [Member]	Sep. 30, 2012 Pension Plans [Member] companies	Oct. 02, 2011 Pension Plans [Member]	Sep. 30, 2012 Pension Plans [Member] Washington Post Newspaper [Member]	Apr. 03, 2011 Pension Plans [Member] Robinson Terminal Warehouse [Member]	Mar. 31, 2012 Pension Plans [Member] Post Newsweek Media [Member]	Sep. 30, 2012 Berkshire Hathaway Common Stock [Member] Pension Plans [Member]	Dec. 31, 2011 Berkshire Hathaway Common Stock [Member] Pension Plans [Member]	Sep. 30, 2012 Foreign Investments [Member] Pension Plans [Member]	Sep. 30, 2012 Single Equity Concentration [Member] Pension Plans [Member]	Dec. 31, 2011 Single Equity Concentration [Member] Pension Plans [Member]	Sep. 30, 2012 Concentration In Single Entity, Type Of Industry, Foreign Country Or Individual Fund [Member] Pension Plans [Member]	Sep. 30, 2012 Other fixed income securities [Member] Pension Plans [Member]	Sep. 30, 2012 Geographic Concentration [Member] Foreign Investments [Member] Pension Plans [Member] country	Dec. 31, 2011 Geographic Concentration [Member] Foreign Investments [Member] Pension Plans [Member]
Retirement Benefits Disclosure [Line Items]
Early retirement program expense	$ 8,508,000	$ 430,000		$ 7,486,000	$ 0	$ 8,508,000	$ 430,000	$ 7,500,000	$ 400,000	$ 1,000,000
Number of investment companies actively managing plan assets				2		2
Defined benefit plan, target allocation maximum percentage of assets, equity securities													24.00%
Defined benefit plan, target allocation maximum percentage of assets, singular equity security, without prior approval by plan administrator											20.00%			10.00%
Defined benefit plan, target allocation percentage of assets, fixed-income securities, range minimum																	10.00%
Minimum percentage of plan assets considered as significant concentrations in pension plans																10.00%
Investment in Marketable Equity Securities	379,928,000		303,201,000
Value of investments											$ 178,100,000	$ 154,000,000		$ 206,300,000	$ 222,400,000			$ 222,600,000	$ 241,400,000
Percentage of total plan assets														10.00%	12.00%			11.00%	13.00%
Number of investments the companys pension plan held which individually exceed 10% of total plan assets														1
Number of foreign countries for which the companys pension plan holds investments that exceed 10% of total plan assets																		1