CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
Net income	$ 276.3	$ 161.8	$ 398.9	$ 603.4
Other comprehensive income:
Foreign currency translation (losses) gain		(1.0)	0.2	(2.8)
Defined benefit pension plan:
Actuarial (losses) gain arising during period, net of tax		(1.2)	(0.1)	5.9
Amortization of actuarial gain and prior service cost included in net periodic pension cost, net of tax	0.1	0.1	0.4	0.5
Total defined benefit pension plan, net of tax	0.1	(1.1)	0.3	6.4
Unrealized loss on available-for-sale securities	(0.3)		(0.5)
Other comprehensive (losses) gain, net of tax	(0.2)	(2.1)		3.6
Comprehensive income	$ 276.1	$ 159.7	$ 398.9	$ 607.0