Income Taxes - Narrative (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income Tax Contingency [Line Items]
Deferred tax assets valuation allowance increased	$ 28.5	$ (43.5)	$ 21.9
Recognized tax benefit from net operating loss carryforwards, federal		7.9
Recognized tax benefit from net operating loss carryforwards, state		$ 1.4