Pension and Profit Sharing Plans - Benefit Obligations and Net Periodic Pension Cost and Rate of Return on Plan Assets (Detail)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Fair Value Measurement Inputs Disclosure [Line Items]
Weighted average discount rate	3.75%	4.65%	5.25%
Expected long-term rate of return on assets	6.25%	6.75%	6.75%