Effect of Master Netting Arrangements on Presentation of Derivative Assets and Liabilities in Consolidated Statements of Financial Condition (Detail) $ in Thousands	Dec. 31, 2016 USD ($)
Derivative Financial Instruments, Liabilities
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Liabilities	$ 23,728
Gross Amounts Offset in the Statement of Condition	16,588
Net Amounts of Liabilities Presented in the Statement of Condition	7,140
Financial Instruments	0
Cash Collateral Received	0
Net Amount	7,140
Derivative Financial Instruments, Assets
Derivatives, Fair Value [Line Items]
Gross Amounts Of Recognized Assets	20,422	[1]
Gross Amounts Offset in the Statement of Condition	17,861
Net Amounts of Assets Presented in the Statement of Condition	2,561
Financial Instruments	0
Cash Collateral Received	0
Net Amount	$ 2,561

[1] Included $1.9 million to purchase Treasury options.