Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Property and Equipment at Cost and Depreciable Useful Lives

Cost and estimated useful lives of property and equipment by function are as follows:

Category	2017		2016		Life
	(In millions of dollars)
Land	$	3.8	$	3.8		—
Work in process	5.3		0.8			—
Buildings and improvements	64.9		61.1		15	to	45 years
Computer hardware and software	154.2		145.0		3	to	12 years
Equipment, furniture and fixtures	37.9		33.8			5	years
Leasehold improvements	25.7		25.5		The lesser of the life of the lease or 5 years.
Total property and equipment	$	291.8	$	270.0