Investments (Narrative) (Details) (USD $)	12 Months Ended									3 Months Ended					12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011 Investment	Dec. 31, 2013 Berkshire Hathaway Inc [Member]	Dec. 31, 2012 Berkshire Hathaway Inc [Member]	Dec. 31, 2013 Berkshire Hathaway Inc [Member] Class A Common Stock [Member]	Dec. 31, 2012 Berkshire Hathaway Inc [Member] Class A Common Stock [Member]	Dec. 31, 2013 Berkshire Hathaway Inc [Member] Class B Common Stock [Member]	Dec. 31, 2012 Berkshire Hathaway Inc [Member] Class B Common Stock [Member]	Oct. 02, 2011 Corinthian Colleges, Inc. [Member]	Apr. 03, 2011 Corinthian Colleges, Inc. [Member]	Dec. 31, 2012 Bowater Mersey Paper Company [Member]	Oct. 02, 2011 Bowater Mersey Paper Company [Member]	Dec. 31, 2013 Classified Ventures LLC [Member]	Dec. 31, 2013 Strayer Education Inc. [Member]	Dec. 31, 2012 Strayer Education Inc. [Member]
Schedule of Investments [Line Items]
Shares held in investee company						2,214	2,214	424,250	424,250
Company's investments in marketable equity securities	$ 487,156,000	$ 380,087,000		$ 444,200,000	$ 334,900,000
Percentage of total fair value of the Company's investments in marketable equity securities				91.00%	88.00%
Percentage of common stock held by investee company				23.00%
Percentage of investment held in related party investee company				less than 1%
Net unrealized gains	289,438,000	184,255,000		286,900,000	177,600,000
Amount of time investment had been in an unrealized loss position											over six months				about six months	about six months
Impairment write-down on a marketable equity security	10,438,000	17,998,000	53,793,000							23,100,000	30,700,000				10,400,000	18,000,000
New investments in marketable equity securities	15,000,000	45,000,000	0
Proceeds from sales of marketable equity securities	3,600,000	2,000,000
Gain on sales of marketable equity securities	900,000	500,000
Sales of marketable equity securties			0
Ownership percentage of investment in affiliate														16.50%
Impairment charge on the Company's investment in affiliate													9,200,000
Percentage of equity method investment ownership sold												49.00%
Realized gain (loss) on disposal of investment in affiliate												0
Fair Value of investment owned												$ 0