Quarterly Results of Operations (unaudited) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Results of Operations (unaudited)
Revenues	$ 1,697	$ 1,577	$ 1,426	$ 1,571	$ 1,372	$ 1,460	$ 1,160	$ 1,520	$ 6,271	$ 5,512	$ 4,824
Benefits and expenses	1,227	1,179	1,163	1,135	1,207	1,190	1,230	986	4,704	4,613	4,466
Income (loss) from operations before income taxes and noncontrolling interest	470	398	263	436	165	270	(70)	534	1,567	899	358
Net income (loss)	314	267	177	290	119	184	(38)	354	1,048	619	268
Less: Net income (loss) attributable to noncontrolling interest in consolidated entity – Exchange	278	221	133	253	89	133	(81)	318	885	459	99
Net income (loss) attributable to Indemnity	36	46	44	37	30	51	43	36	163	160	169
Indemnity
Quarterly Results of Operations (unaudited)
Income (loss) from operations before income taxes and noncontrolling interest									247	241	256
Net income (loss) attributable to Indemnity									$ 163	$ 160	$ 169
Class A | Indemnity
Net income attributable to Indemnity per share
Common stock - basic (in dollars per share)	$ 0.75	$ 0.98	$ 0.95	$ 0.78	$ 0.63	$ 1.08	$ 0.90	$ 0.76	$ 3.46	$ 3.38	$ 3.45
Common stock - diluted (in dollars per share)	$ 0.67	$ 0.87	$ 0.84	$ 0.69	$ 0.56	$ 0.96	$ 0.80	$ 0.67	$ 3.08	$ 2.99	$ 3.08
Class B | Indemnity
Net income attributable to Indemnity per share
Common stock - basic (in dollars per share)	$ 113.00	$ 147.00	$ 142.00	$ 117.00	$ 94	$ 162.00	$ 135.00	$ 114.00	$ 520.00	$ 505.00	$ 522.00
Common stock - diluted (in dollars per share)	$ 113.00	$ 147.00	$ 142.00	$ 117.00	$ 94	$ 162.00	$ 135.00	$ 114.00	$ 519.00	$ 505.00	$ 522.00