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, 2015	Mar. 31, 2014	Dec. 31, 2014
Reconciliation of the beginning and ending balances of Indemnity's shareholders' equity and the noncontrolling interest
Balance, beginning of period	$ 7,983	$ 7,550	$ 7,550
Net income	136	109	573
Change in accumulated other comprehensive income (loss), net of tax	50	72	0
Net purchase of treasury stock			(19)
Dividends declared:
Balance, end of period	8,137		7,983
Class A
Dividends declared:
Dividends declared	(32)		(120)
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	703	734	734
Net income	39		168
Change in accumulated other comprehensive income (loss), net of tax	0	3	(59)
Net purchase of treasury stock			(19)
Dividends declared:
Balance, end of period	710		703
Indemnity | Class A
Dividends declared:
Dividends declared (in dollars per share)	$ 0.6810	$ 0.6350	$ 2.4125
Dividends declared	(32)		(120)
Indemnity | Class B
Dividends declared:
Dividends declared (in dollars per share)	$ 102.1500	$ 95.2500	$ 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	7,280	6,816	6,816
Net income	97		405
Change in accumulated other comprehensive income (loss), net of tax	50		59
Dividends declared:
Balance, end of period	$ 7,427		$ 7,280