Consolidated Statements of Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues
Premiums	$ 73,385.1	$ 68,389.8	$ 66,119.1
Administrative fees	4,976.6	4,590.6	4,031.9
Other revenue	43.1	41.3	40.4
Total operating revenue	78,404.8	73,021.7	70,191.4
Net investment income	677.6	724.4	659.1
Net realized gains on investments	157.5	177.0	271.9
Other than temporary impairment losses on investments:
Total other-than-temporary impairment losses on investments	(99.9)	(56.2)	(100.6)
Portion of other-than-temporary impairment losses recognized in other comprehensive income	16.5	7.2	1.7
Other-than-temporary impairment losses recognized in income	(83.4)	(49.0)	(98.9)
Total revenues	79,156.5	73,874.1	71,023.5
Expenses
Benefit expense	61,116.9	56,854.9	56,237.1
Selling, general and administrative expense:
Selling expense	1,441.1	1,490.1	1,526.9
General and administrative expense	11,093.7	10,258.3	8,426.0
Total selling, general and administrative expense	12,534.8	11,748.4	9,952.9
Interest expense	653.0	600.7	602.7
Amortization of other intangible assets	230.1	220.9	245.3
(Gain) loss on extinguishment of debt	(9.3)	81.1	145.3
Total expenses	74,525.5	69,506.0	67,183.3
Income from continuing operations before income tax expense	4,631.0	4,368.1	3,840.2
Income tax expense	2,071.0	1,808.0	1,205.9
Income from continuing operations	2,560.0	2,560.1	2,634.3
Income (loss) from discontinued operations, net of tax	0.0	9.6	(144.6)
Net income	$ 2,560.0	$ 2,569.7	$ 2,489.7
Basic net income (loss) per share:
Basic - continuing operations (in dollars per share)	$ 9.73	$ 9.28	$ 8.83
Basic - discontinued operations (in dollars per share)	0.00	0.03	(0.49)
Basic net income per share	9.73	9.31	8.34
Diluted net income (loss) per share:
Diluted - continuing operations (in dollars per share)	9.38	8.96	8.67
Diluted - discontinued operations (in dollars per share)	0.00	0.03	(0.47)
Diluted net income per share	9.38	8.99	8.20
Dividends per share	$ 2.50	$ 1.75	$ 1.50