Employee Benefit Plans - Schedule of Amounts in AOCI on Consolidated Statement of Financial Condition Expected to be Recognized (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Prior service cost	$ 2,600
Net actuarial loss (gain)	4,821
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Prior service cost	2,600
Net actuarial loss (gain)	$ 4,821