Activity in Allowance for Credit Losses (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Disclosure Activity in Allowance for Credit Losses [Abstract]
Balance at Beginning of Period	$ 4.5	$ 1.5	$ 1.5	$ 1.5
Provisions	0	0	3.0	0
Balance at End of Period	$ 4.5	$ 1.5	$ 4.5	$ 1.5