Income Tax (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Sep. 30, 2011
Effective Income Tax Rate, Continuing Operations	35.00%
Operating Loss Carryforwards, Expiration Dates	$7.5
Deferred Tax Liability Not Recognized, Cumulative Amount of Temporary Difference	$ 8.5	$ 8.5	$ 8.5
Domestic Tax Authority [Member]
Effective Income Tax Rate, Continuing Operations	35.00%