Schedule II - Condensed Financial Information, Statements of Income (Details) - USD ($) $ in Millions	3 Months Ended											12 Months Ended
	Dec. 31, 2015		Sep. 30, 2015		Jun. 30, 2015		Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating expenses:
Loss on extinguishment of debt												$ 100	$ 0	$ 0
Total operating expenses												8,982	8,174	7,595
Income before Income Taxes	$ 659		$ 878		$ 936		$ 854	$ 732	$ 818	$ 901	$ 853	3,327	3,304	2,176
Income tax expense (benefit)												1,250	1,210	698
Shareholders' Net Income	$ 426	[1]	$ 547	[1]	$ 588	[2]	$ 533	$ 467	$ 534	$ 573	$ 528	2,094	2,102	1,476
Shareholders' other comprehensive income (loss):
Net unrealized appreciation (depreciation) on securities												(202)	143	(410)
Net unrealized appreciation (depreciation), derivatives												15	11	9
Net translation of foreign currencies												(212)	(144)	13
Postretirement benefits liability adjustment												85	(426)	539
Shareholders' other comprehensive income (loss)												(314)	(416)	151
Shareholders' comprehensive income (loss)												1,780	1,686	1,627
Parent Company [Member]
Operating expenses:
Interest Expense												246	258	264
Intercompany Interest Expense												2	5	2
Other operating expenses												147	82	69
Loss on extinguishment of debt												100	0	0
Total operating expenses												495	345	335
Income before Income Taxes												(495)	(345)	(335)
Income tax expense (benefit)												(135)	(89)	(109)
(Loss) of parent company												(360)	(256)	(226)
Equity in income from subsidiaries												2,454	2,358	1,702
Shareholders' Net Income												2,094	2,102	1,476
Shareholders' other comprehensive income (loss):
Net unrealized appreciation (depreciation) on securities												(202)	143	(410)
Net unrealized appreciation (depreciation), derivatives												15	11	9
Net translation of foreign currencies												(212)	(144)	13
Postretirement benefits liability adjustment												85	(426)	539
Shareholders' other comprehensive income (loss)												(314)	(416)	151
Shareholders' comprehensive income (loss)												$ 1,780	$ 1,686	$ 1,627

[1] Shareholders’ net income includes after-tax charges of $29 million in the third quarter of 2015 and $28 million in the fourth quarter of 2015 for advisory, legal and other transactions costs directly related to the Company’s proposed merger with Anthem. See Note 3 to the Consolidated Financial Statements for additional details.

[2] Shareholders’ net income includes an after-tax charge of $65 million for the early extinguishment of debt in the second quarter of 2015. See Note 15 to the Consolidated Financial Statements for additional details.