Reinsurance (Tables)

12 Months Ended

Dec. 31, 2016

Reinsurance Disclosures [Abstract]

Summary Of Direct, Assumed And Ceded Premiums Written And Earned

A summary of direct, assumed and ceded premiums written and earned for the years ended December 31 is as follows:

	2016						2015						2014
	Written			Earned			Written			Earned			Written			Earned
Direct	$	78,200.4		$	78,726.2		$	72,925.5		$	73,259.2		$	68,628.6		$	68,304.3
Assumed	217.4			217.3			221.8			221.9			192.3			194.0
Ceded	(79.8		)	(83.4		)	(95.8		)	(96.0		)	(108.5		)	(108.5		)
Net premiums	$	78,338.0		$	78,860.1		$	73,051.5		$	73,385.1		$	68,712.4		$	68,389.8
Percentage—assumed to net premiums	0.3		%	0.3		%	0.3		%	0.3		%	0.3		%	0.3		%

Summary Of Net Premiums Written And Earned By Segment

A summary of net premiums written and earned by segment (see Note 19, “Segment Information”) for the years ended December 31 is as follows:

	2016				2015				2014
	Written		Earned		Written		Earned		Written		Earned
Reportable segments:
Commercial and Specialty Business	$	33,355.6	$	33,831.5	$	33,016.9	$	33,078.0	$	35,084.7	$	35,045.2
Government Business	44,982.4		45,028.6		40,034.6		40,307.1		33,627.7		33,344.6
Net premiums	$	78,338.0	$	78,860.1	$	73,051.5	$	73,385.1	$	68,712.4	$	68,389.8

Effect Of Reinsurance On Benefit Expense

The effect of reinsurance on benefit expense for the years ended December 31 is as follows:

	2016			2015			2014
Direct	$	67,221.7		$	61,674.0		$	57,496.6
Assumed	184.9			192.2			182.4
Ceded	(572.2		)	(749.3		)	(824.1		)
Net benefit expense	$	66,834.4		$	61,116.9		$	56,854.9

Effect Of Reinsurance On Certain Assets And Liabilities

The effect of reinsurance on certain assets and liabilities at December 31 is as follows:

	2016		2015
Policy liabilities, assumed	$	47.2	$	56.7
Unearned income, assumed	0.6		0.5
Premiums payable, ceded	5.2		9.3
Premiums receivable, assumed	25.9		23.2