Other Non-Operating Income (Expense) (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Investment [Line Items]
Gain on Berkshire marketable equity securities exchange	$ 266,733,000	$ 0	$ 266,733,000	$ 0
Proceeds from sale of building			158,000,000
Gain on sale of headquarters building	0	0	127,670,000	0
Berkshire Exchange Transaction [Member]
Investment [Line Items]
Amount of Cash Exchanged to Berkshire	327,700,000		327,700,000
Common Class B [Member] | Berkshire Exchange Transaction [Member]
Investment [Line Items]
Number of shares received in Berkshire Hathaway agreement	1,620,190		1,620,190
Berkshire Hathaway Inc [Member] | Berkshire Exchange Transaction [Member]
Investment [Line Items]
Gain on Berkshire marketable equity securities exchange	$ 266,733,000
Berkshire Hathaway Inc [Member] | Common Class A [Member] | Berkshire Exchange Transaction [Member]
Investment [Line Items]
Number of Berkshire Shares Exchanged	2,107		2,107
Berkshire Hathaway Inc [Member] | Common Class B [Member] | Berkshire Exchange Transaction [Member]
Investment [Line Items]
Number of Berkshire Shares Exchanged	1,278		1,278