Consolidated Statements of Comprehensive Income (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Comprehensive income:
Net income	$ 203.9	$ 243.9	$ 204.7
Other comprehensive income, before tax:
Cumulative translation adjustment	(31.3)	13.7	(25.4)
Derivative financial instruments	4.6	(3.1)	19.0
Accrued benefit cost	38.3	(11.6)	(31.9)
Unrealized gain on investment		0.5	0.2
Total other comprehensive income (loss), before tax	11.6	(0.5)	(38.1)
Income tax (provision) benefit related to other comprehensive income (loss)	(16.8)	3.8	6.2
Comprehensive income	$ 198.7	$ 247.2	$ 172.8