Indemnity Earnings Per Share (Details) (Indemnity, USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Mar. 31, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Class A
Reconciliation of the numerators and denominators used in the basic and diluted per-share computations
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)	$ 44	$ 43		$ 80	$ 78
Weighted shares (denominator) (in shares)	46,693,333	47,492,305		46,733,925	47,619,852
Per-share amount (in dollars per share)	$ 0.95	$ 0.90		$ 1.73	$ 1.65
Dilutive effect of stock-based awards
Allocated net income (numerator) (in dollars)	0	0		0	0
Weighted shares (denominator) (in shares)	92,126	79,943		92,126	79,943
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	6,108,000
Income available to stockholders on equivalent shares
Allocated net income (numerator) (in dollars)	44	43		81	79
Weighted shares (denominator) (in shares)	52,886,259	53,677,848		52,926,851	53,807,795
Per-share amount (in dollars per share)	$ 0.84	$ 0.80		$ 1.54	$ 1.47
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%
Class B common stock shares converted into Class A common stock shares (in shares)			2	0
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	2,545
Per-share amount (in dollars per share)	$ 142.00	$ 135.00		$ 259.00	$ 249.00
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	2,545
Per-share amount (in dollars per share)	$ 142.00	$ 135.00		$ 259.00	$ 249.00