Unaudited Quarterly Results (Tables)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Schedule of Quarterly Financial Information

The following is a summary of our unaudited quarterly results of operations for 2017 and 2016:

	2017
	4th		3rd		2nd		1st
	(in millions of dollars, except share data)
Premium Income	$	2,158.4	$	2,153.6	$	2,142.2	$	2,142.9
Net Investment Income	619.8		609.0		620.5		602.4
Net Realized Investment Gain	11.4		9.8		8.1		11.0
Total Revenue	2,839.2		2,819.1		2,822.0		2,806.5
Income Before Income Tax	345.3		366.8		361.6		330.3
Net Income	266.9		252.3		245.1		229.9
Net Income Per Common Share
Basic	1.19		1.12		1.08		1.00
Assuming Dilution	1.19		1.12		1.07		1.00

	2016
	4th		3rd		2nd		1st
	(in millions of dollars, except share data)
Premium Income	$	2,099.2	$	2,089.4	$	2,081.6	$	2,087.5
Net Investment Income	617.9		611.4		623.3		606.4
Net Realized Investment Gain (Loss)	28.4		11.0		5.3		(20.5		)
Total Revenue	2,796.5		2,763.3		2,761.3		2,725.4
Income Before Income Tax	371.2		332.1		340.2		304.2
Net Income	248.0		236.0		236.8		210.6
Net Income Per Common Share
Basic	1.07		1.01		1.00		0.88
Assuming Dilution	1.07		1.01		1.00		0.88