Earnings Per Share (Details) (Indemnity, USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Class A
Indemnity Earnings Per Share Calculation
Class A common stock shares issued upon conversion of Class B common stock shares (in shares)	4,800
Income available to stockholders
Allocated net income (numerator) (in dollars)	$ 36	$ 44
Weighted shares (denominator)	47,749,799	49,789,056
Per-share amount (in dollars per share)	$ 0.76	$ 0.88
Dilutive effect of stock-based awards
Allocated net income (numerator) (in dollars)	0	0
Weighted shares (denominator) (in shares)	72,245	69,382
Assumed conversion of Class B shares
Allocated net income (numerator) (in dollars)	0	0
Weighted shares (denominator)	6,108,000	6,110,400
Income available to stockholders on equivalent shares
Allocated net income (numerator) (in dollars)	36	44
Weighted shares (denominator) (in shares)	53,930,044	55,968,838
Per-share amount (in dollars per share)	$ 0.67	$ 0.78
Class B
Indemnity Earnings Per Share Calculation
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
Income available to stockholders
Allocated net income (numerator) (in dollars)	0	0
Weighted shares (denominator)	2,545	2,546
Per-share amount (in dollars per share)	$ 113.56	$ 126.48
Income available to stockholders on equivalent shares
Allocated net income (numerator) (in dollars)	$ 0	$ 0
Weighted shares (denominator) (in shares)	2,545	2,546
Per-share amount (in dollars per share)	$ 113.56	$ 126.48