Indemnity Shareholders' Equity and Noncontrolling Interest (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Reconciliation of the beginning and ending balances of Indemnity's shareholders' equity and the noncontrolling interest
Balance, beginning of period	$ 7,550	$ 6,791	$ 6,791
Net income	109	290	1,048
Change in other comprehensive income (loss), net of tax	72	(22)	(144)
Net purchase of treasury stock	(11)		(32)
Dividends declared:
Balance, end of period	7,690		7,550
Class A
Dividends declared:
Dividends declared	(30)		(112)
Class B
Dividends declared:
Dividends declared	0		(1)
Indemnity
Reconciliation of the beginning and ending balances of Indemnity's shareholders' equity and the noncontrolling interest
Balance, beginning of period	734	642	642
Net income	46		163
Change in other comprehensive income (loss), net of tax	3		74
Net purchase of treasury stock	(11)		(32)
Dividends declared:
Balance, end of period	742		734
Indemnity | Class A
Dividends declared:
Dividends declared (in dollars per share)	$ 0.6350	$ 0.5925	$ 2.4125
Dividends declared	(30)		(112)
Indemnity | Class B
Dividends declared:
Dividends declared (in dollars per share)	$ 95.2500	$ 88.8750	$ 361.8750
Dividends declared	0		(1)
Exchange
Reconciliation of the beginning and ending balances of Indemnity's shareholders' equity and the noncontrolling interest
Balance, beginning of period	6,816	6,149	6,149
Net income	63		885
Change in other comprehensive income (loss), net of tax	69		(218)
Dividends declared:
Balance, end of period	$ 6,948		$ 6,816