Consolidated Statements Of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Consolidated Statements Of Comprehensive Income [Abstract]
Net income	$ 65.1	$ 52.9	$ 187.2	$ 159.8
Other comprehensive income (loss), net of tax:
Unrealized loss on securities			(0.1)
Other comprehensive income (loss)			(0.1)
Comprehensive income	$ 65.1	$ 52.9	$ 187.1	$ 159.8