Consolidated Statements of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Statement Of Comprehensive Income [Abstract]
Shareholders' Net Income	$ 57	$ 371
Net unrealized appreciation (deprecation) on securities:
Net unrealized appreciation (depreciation), fixed maturities	(72)	23
Net unrealized appreciation (depreciation), equity securities	2	1
Net unrealized appreciation (depreciation) on securities	(70)	24
Net unrealized appreciation (depreciation), derivatives	3	(5)
Net translation of foreign currencies	(58)	35
Postretirement benefits liability adjustment	40	11
Shareholders' other comprehensive income (loss)	(85)	65
Shareholders' comprehensive income (loss)	(28)	436
Comprehensive income attributable to noncontrolling interest:
Net income attributable to redeemable noncontrolling interest	2	0
Other comprehensive income attributable to redeemable noncontrolling interest	(3)	0
Total comprehensive income (loss)	$ (29)	$ 436