Income Taxes - Additional Information (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Income Taxes [Line Items]
Effective tax rate	37.60%	37.90%	37.50%	37.90%
Percentage of tax position benefit maximum than being realized upon ultimate settlement			50.00%