Indemnity Capital Stock (Details) (Indemnity, USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended	3 Months Ended
	Oct. 31, 2011 Class A	Mar. 31, 2012 Class A	Mar. 31, 2012 Class B	Dec. 31, 2011 Class B
Capital Stock
Ratio for converting shares of Class B common stock into shares of Class A common stock, numerator (in Class A shares)			2,400	2,400
Ratio for converting shares of Class B common stock into shares of Class A common stock, denominator (in Class B shares)			1	1
Class B common stock shares converted into Class A common stock shares (in shares)			2
Class A common stock shares issued upon conversion of Class B common stock shares (in shares)		4,800
Amount of authorized stock repurchase approved for continuation	$ 150
Approximate amount of repurchase authority remaining under stock repurchase program		$ 120