Consolidated Statements of Shareholders' Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended											12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013		Sep. 30, 2013	Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement Of Comprehensive Income [Abstract]
Shareholders' Net Income	$ 467	$ 534	$ 573	$ 528	$ 361	[1]	$ 553	$ 505	[2]	$ 57	[3]	$ 2,102	$ 1,476	$ 1,623
Shareholders' other comprehensive income (loss):
Net unrealized appreciation (depreciation) on securities												143	(410)	147
Net unrealized appreciation (depreciation), derivatives												11	9	(5)
Net translation of foreign currencies												(144)	13	66
Postretirement benefits liability adjustment												(426)	539	(92)
Shareholders' other comprehensive income (loss)												(416)	151	116
Shareholders' comprehensive income (loss)												$ 1,686	$ 1,627	$ 1,739

[1] The fourth quarter of 2013 includes an after-tax charge of $40 million for an organizational efficiency plan.

[2] The second quarter of 2013 includes an after-tax charge of $24 million for the Pharmacy Benefits Manager (“PBM”) partnering agreement with Catamaran.

[3] The first quarter of 2013 includes an after-tax gain of $25 million for the GMIB business, an after-tax charge of $507 million for the transaction with Berkshire to effectively exit the Run-off Reinsurance business, and an after-tax charge of $51 million related to the disability claims regulatory matter in the Group Disability and Life segment.