Indemnity Earnings Per Share (Details) (Indemnity, USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Class A
Income available to stockholders
Allocated net income (numerator) (in dollars)	$ 46	$ 51	$ 126	$ 129
Weighted shares (denominator) (in shares)	46,656,911	47,188,741	46,707,971	47,476,693
Per-share amount (in dollars per share)	$ 0.98	$ 1.08	$ 2.71	$ 2.73
Dilutive effect of stock-based awards
Allocated net income (numerator) (in dollars)	0	0	0	0
Weighted shares (denominator) (in shares)	93,539	80,505	93,539	80,505
Assumed conversion of Class B shares
Allocated net income (numerator) (in dollars)	0	0	1	1
Weighted shares (denominator) (in shares)	6,100,800	6,105,600	6,100,800	6,105,600
Income available to stockholders on equivalent shares
Allocated net income (numerator) (in dollars)	46	51	127	130
Weighted shares (denominator) (in shares)	52,851,250	53,374,846	52,902,310	53,662,798
Per-share amount (in dollars per share)	$ 0.87	$ 0.96	$ 2.41	$ 2.43
Class B
Reconciliation of the numerators and denominators used in the basic and diluted per-share computations
Ratio for converting shares of Class B common stock into shares of Class A common stock (as a percent)	2400.00%		2400.00%		2400.00%
Income available to stockholders
Allocated net income (numerator) (in dollars)	0	0	1	1
Weighted shares (denominator) (in shares)	2,542	2,544	2,542	2,544
Per-share amount (in dollars per share)	$ 147.00	$ 162.00	$ 406.00	$ 411.00
Income available to stockholders on equivalent shares
Allocated net income (numerator) (in dollars)	$ 0	$ 0	$ 1	$ 1
Weighted shares (denominator) (in shares)	2,542	2,544	2,542	2,544
Per-share amount (in dollars per share)	$ 147.00	$ 162.00	$ 406.00	$ 411.00