Segment Data (Narrative) (Detail)	9 Months Ended		12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Segment Reporting, Revenue Reconciling Item [Line Items]
Percentage of revenue generated from the foreign countries	5.90%	2.90%
Percentage of total assets in the foreign countries	6.90%		8.70%