Pension and Postretirement Plans (Narrative) (Details) (USD $)	3 Months Ended							9 Months Ended		12 Months Ended
	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011
Retirement Benefits Disclosure [Line Items]
Total Cost (Benefit)	$ (2,733,000)	$ (2,638,000)	$ (2,729,000)	$ (631,000)	$ (1,134,000)	$ (3,368,000)	$ (3,475,000)	$ (8,100,000)	$ (7,977,000)	$ (8,608,000)	$ (23,219,000)
Early retirement program expense								22,700,000	8,508,000
Sale of Publishing Subsidiaries [Member]
Retirement Benefits Disclosure [Line Items]
Early retirement program expense					7,500,000			22,700,000	8,500,000
Sale of Publishing Subsidiaries [Member] | Discontinued Operations [Member]
Retirement Benefits Disclosure [Line Items]
Additional amount to be transferred to Purchaser related to pension	50,000,000							50,000,000
Pension Plan [Member]
Retirement Benefits Disclosure [Line Items]
Total Cost (Benefit)	2,843,000				12,832,000			34,125,000	18,488,000
Early retirement program expense	0				7,486,000			22,700,000	8,508,000
Number of investment companies actively managing plan assets	2							2
Amount of plan assets managed internally by the company	None							None
Percentage of total plan assets	100.00%			100.00%				100.00%		100.00%
Pension Plan [Member] | Washington Post Newspaper [Member] | Voluntary Retirement Incentive Program [Member] | Discontinued Operations [Member]
Retirement Benefits Disclosure [Line Items]
Early retirement program expense		8,400,000	12,000,000		7,500,000			20,400,000
Pension Plan [Member] | Washington Post Newspaper [Member] | Special Separation Benefits [Member] | Discontinued Operations [Member]
Retirement Benefits Disclosure [Line Items]
Early retirement program expense			2,300,000
Pension Plan [Member] | Post-Newsweek Media [Member] | Voluntary Retirement Incentive Program [Member] | Discontinued Operations [Member]
Retirement Benefits Disclosure [Line Items]
Early retirement program expense							1,000,000
Pension Plan [Member] | Sale of Publishing Subsidiaries [Member] | Discontinued Operations [Member]
Retirement Benefits Disclosure [Line Items]
Total Cost (Benefit)	5,600,000				13,900,000			42,200,000	26,300,000
Supplemental Executive Retirement Plan (SERP) [Member]
Retirement Benefits Disclosure [Line Items]
Total Cost (Benefit)	2,177,000				1,899,000			6,531,000	5,697,000
Supplemental Executive Retirement Plan (SERP) [Member] | Sale of Publishing Subsidiaries [Member] | Discontinued Operations [Member]
Retirement Benefits Disclosure [Line Items]
Total Cost (Benefit)	200,000				200,000			600,000	500,000
Other Postretirement Plans [Member]
Retirement Benefits Disclosure [Line Items]
Total Cost (Benefit)	(574,000)				(310,000)			(5,284,000)	(929,000)
Settlement gain	0				0			(3,471,000)	0
Other Postretirement Plans [Member] | Daily Herald [Member] | Discontinued Operations [Member]
Retirement Benefits Disclosure [Line Items]
Settlement gain								(3,500,000)
Other Postretirement Plans [Member] | Sale of Publishing Subsidiaries [Member] | Discontinued Operations [Member]
Retirement Benefits Disclosure [Line Items]
Total Cost (Benefit)	(1,500,000)				(600,000)			(2,800,000)	(1,800,000)
Berkshire Hathaway Common Stock [Member] | Pension Plan [Member]
Retirement Benefits Disclosure [Line Items]
Defined benefit plan, target allocation maximum percentage of assets, singular equity security, without prior approval by plan administrator								20.00%
Value of related party investments	228,600,000			179,900,000				228,600,000		179,900,000
Foreign Investments [Member] | Pension Plan [Member]
Retirement Benefits Disclosure [Line Items]
Defined benefit plan, target allocation maximum percentage of assets, equity securities								24.00%
Fixed income securities [Member] | Pension Plan [Member]
Retirement Benefits Disclosure [Line Items]
Defined benefit plan, target allocation percentage of assets, fixed-income securities, range minimum								10.00%
Single Equity Concentration [Member] | Pension Plan [Member]
Retirement Benefits Disclosure [Line Items]
Defined benefit plan, target allocation maximum percentage of assets, singular equity security, without prior approval by plan administrator								10.00%
Value of investments	389,300,000			223,100,000				389,300,000		223,100,000
Percentage of total plan assets	16.00%			11.00%				16.00%		11.00%
Number of investments the company's pension plan held which individually exceed 10% of total plan assets	1			1				1		1
Concentration In Single Entity, Type Of Industry, Foreign Country Or Individual Fund [Member] | Defined Benefit Plan Assets Total [Member] | Pension Plan [Member]
Retirement Benefits Disclosure [Line Items]
Minimum percentage of plan assets considered as significant concentrations in pension plans								10.00%
Geographic Concentration [Member] | Foreign Investments [Member] | Pension Plan [Member]
Retirement Benefits Disclosure [Line Items]
Value of investments	$ 406,400,000			$ 240,400,000				$ 406,400,000		$ 240,400,000
Percentage of total plan assets	16.00%			12.00%				16.00%		12.00%
Number of foreign countries for which the companys pension plan holds investments that exceed 10% of total plan assets	1			1				1		1