Employee Benefit Plans - Summary of Changes in Benefit Obligations, Fair Value of Assets, Funded Status and Amounts Recognized in Consolidated Statements of Financial Condition (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan, Assets for Plan Benefits [Abstract]
Excluding tax benefits on amounts recognized	$ 37,567	$ 30,448