Income Taxes - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Income Tax Examination [Line Items]
Reported tax rate	26.40%	65.00%	28.10%	27.60%
Income tax expense, correction to a deferred tax asset		$ 1.7
Accrual for tax contingencies	0.8		0.6
Effective tax rate estimate			21.30%
State of New Jersey
Income Tax Examination [Line Items]
Income tax expense, tax law change		$ 0.7