Indemnity Earnings Per Share (Details) - Indemnity - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Class A
Income available to stockholders (Basic EPS:)
Allocated net income (numerator) (in dollars)	$ 50	$ 47	$ 144	$ 141
Weighted shares (denominator) (in shares)	46,189,068	46,189,068	46,189,068	46,267,694
Per-share amount (in dollars per share)	$ 1.06	$ 1.01	$ 3.10	$ 3.05
Dilutive effect of stock-based awards
Allocated net income (numerator) (in dollars)	$ 0	$ 0	$ 0	$ 0
Weighted shares (denominator) (in shares)	312,215	97,296	309,915	97,296
Assumed conversion of Class B shares
Allocated net income (numerator) (in dollars)	$ 0	$ 0	$ 1	$ 1
Weighted shares (denominator) (in shares)	6,100,800	6,100,800	6,100,800	6,100,800
Income available to stockholders on equivalent shares (Diluted EPS:)
Allocated net income (numerator) (in dollars)	$ 50	$ 47	$ 145	$ 142
Weighted shares (denominator) (in shares)	52,602,083	52,387,164	52,599,783	52,465,790
Per-share amount (in dollars per share)	$ 0.94	$ 0.90	$ 2.75	$ 2.71
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 (Basic EPS:)
Allocated net income (numerator) (in dollars)	$ 1	$ 0	$ 1	$ 1
Weighted shares (denominator) (in shares)	2,542	2,542	2,542	2,542
Per-share amount (in dollars per share)	$ 160	$ 151	$ 466	$ 458
Income available to stockholders on equivalent shares (Diluted EPS:)
Allocated net income (numerator) (in dollars)	$ 1	$ 0	$ 1	$ 1
Weighted shares (denominator) (in shares)	2,542	2,542	2,542	2,542
Per-share amount (in dollars per share)	$ 159	$ 151	$ 465	$ 457