Employee Benefit Plans - Summary of Changes in Benefit Obligations, the Fair Value of Assets, Funded Status and Amounts Recognized in the Consolidated Statements of Financial Condition (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
Excluding tax benefits on amounts recognized	$ 25,989	$ 14,183