Consolidated Statements Of Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues
Premiums	$ 20,797.0	$ 19,786.1	$ 62,561.4	$ 58,723.0
Administrative fees	1,289.2	1,330.0	4,031.3	3,956.8
Other revenue	10.5	9.1	21.5	29.3
Total operating revenue	22,096.7	21,125.2	66,614.2	62,709.1
Net investment income	220.2	200.9	627.6	566.9
Net realized gains (losses) on financial instruments	114.7	88.8	138.2	(23.8)
Other-than-temporary impairment losses on investments:
Total other-than-temporary impairment losses on investments	(5.6)	(15.1)	(22.5)	(134.1)
Portion of other-than-temporary impairment losses recognized in other comprehensive income	0.0	4.1	1.6	30.5
Other-than-temporary impairment losses recognized in income	(5.6)	(11.0)	(20.9)	(103.6)
Total revenues	22,426.0	21,403.9	67,359.1	63,148.6
Expenses
Benefit expense	18,103.6	16,922.5	53,563.6	49,266.5
Selling, general and administrative expense:
Selling expense	347.9	338.5	1,042.0	1,039.9
General and administrative expense	2,663.2	2,786.1	8,214.2	8,254.0
Total selling, general and administrative expense	3,011.1	3,124.6	9,256.2	9,293.9
Interest expense	150.5	172.9	575.4	545.7
Amortization of other intangible assets	41.9	47.4	124.3	145.7
Total expenses	21,307.1	20,267.4	63,519.5	59,251.8
Income before income tax expense	1,118.9	1,136.5	3,839.6	3,896.8
Income tax expense	372.0	518.7	1,227.5	1,795.4
Net income	$ 746.9	$ 617.8	$ 2,612.1	$ 2,101.4
Net income per share
Basic net income per share	$ 2.87	$ 2.35	$ 9.92	$ 8.00
Diluted net income per share	2.80	2.30	9.70	7.84
Dividends per share	$ 0.70	$ 0.65	$ 2.00	$ 1.95