Income Taxes (Narrative) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Income Taxes [Line Items]
U.S. federal tax rate	35.00%	35.00%
Unrecognized income tax benefits	$ 5.7		$ 4.2
Recognized additional liabilities	$ 0.3	$ 0.1