Consolidated Statements Of Operations - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues
Net earned premiums	$ 4,404.1	$ 5,007.3	$ 8,351.0
Fees and other income	1,383.1	1,422.5	1,303.5
Net investment income	493.8	515.7	626.2
Net realized gains on investments, excluding other-than-temporary impairment losses	31.0	169.1	36.8
Total other-than-temporary impairment losses	(0.9)	(6.6)	(7.2)
Portion of net loss recognized in other comprehensive income, before taxes	0.0	(0.3)	2.2
Net other-than-temporary impairment losses recognized in earnings	(0.9)	(6.9)	(5.0)
Amortization of deferred gains and gains on disposal of businesses	103.9	394.5	13.0
Gain on pension plan curtailment	0.0	29.6	0.0
Total revenues	6,415.0	7,531.8	10,325.5
Benefits, losses and expenses
Policyholder benefits	1,870.6	1,808.5	4,742.5
Amortization of deferred acquisition costs and value of business acquired	1,340.0	1,351.3	1,402.6
Underwriting, general and administrative expenses	2,710.4	3,442.8	3,924.1
Interest expense	49.5	57.6	55.1
Loss on extinguishment of debt	0.0	23.0	0.0
Total benefits, losses and expenses	5,970.5	6,683.2	10,124.3
Income before (benefit) provision for income taxes	444.5	848.6	201.2
(Benefit) provision for income taxes	(75.1)	283.2	59.6
Net income	$ 519.6	$ 565.4	$ 141.6
Earnings Per Share
Basic (in dollars per share)	$ 9.45	$ 9.23	$ 2.08
Diluted (in dollars per share)	9.39	9.13	2.05
Dividends per share (in dollars per share)	$ 2.15	$ 2.03	$ 1.37
Share Data
Weighted average shares outstanding used in basic per share calculations (in shares)	54,986,654	61,261,288	68,163,825
Plus: Dilutive securities (in shares)	324,378	673,486	853,384
Weighted average shares used in diluted earnings per share calculations (in shares)	55,311,032	61,934,774	69,017,209