Investments (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended			3 Months Ended			3 Months Ended	9 Months Ended
	Sep. 30, 2012	Oct. 02, 2011	Sep. 30, 2012	Oct. 02, 2011 investment	Dec. 31, 2011	Oct. 02, 2011 Corinthian Colleges [Member]	Apr. 03, 2011 Corinthian Colleges [Member]	Sep. 30, 2012 Corinthian Colleges [Member]	Oct. 02, 2011 Bowater Mersey [Member]	Sep. 30, 2012 Strayer Education Inc. [Member]
Investments in marketable equity securities			$ 45,000,000	$ 0
Proceeds from sales of marketable equity securities			2,000,000
Gain on sales of marketable equity securities			500,000
Sales of marketable equity securties				0
Amount of time investment had been in an unrealized loss position							over six months			under three months
Impairment write-down on a marketable equity security	0	23,097,000	0	53,793,000		23,100,000	30,700,000
Company's investments in marketable equity securities	379,928,000		379,928,000		303,201,000			17,800,000
Impairment charge on the Company's investment in affiliate									9,200,000
Unrealized loss on investment	$ 166,097,000		$ 166,097,000		$ 133,930,000					$ 14,100,000