Offsetting of Assets and Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Offsetting Assets and Liabilities [Line Items]
Gross and Net Amounts of Assets Presented in the Statement of Financial Condition	$ 49,124	$ 209,512
Gross Amounts Not Offset in the Statement of Financial Condition, Financial Instruments, Assets	46,375	206,088
Gross Amounts Not Offset in the Statement of Financial Condition, Cash Collateral Received, Assets	1,174	1,310
Net Amount, Assets	1,575	2,114
Gross and Net Amounts of Liabilities Presented in the Statement of Financial Condition	65,692	55,946
Gross Amount Not Offset in the Statement of Financial Condition, Financial Instruments, Liabilities	47,797	42,409
Gross Amounts Not Offset in the Statement of Financial Condition, Cash Collateral Pledged, Liabilities	15,876	12,746
Net Amount, Liabilities	2,019	791
Repurchase Agreements
Offsetting Assets and Liabilities [Line Items]
Gross and Net Amounts of Liabilities Presented in the Statement of Financial Condition	49,540	40,929
Gross Amount Not Offset in the Statement of Financial Condition, Financial Instruments, Liabilities	46,573	40,259
Gross Amounts Not Offset in the Statement of Financial Condition, Cash Collateral Pledged, Liabilities	2,967	670
Net Amount, Liabilities	0
Freestanding Derivatives
Offsetting Assets and Liabilities [Line Items]
Gross and Net Amounts of Assets Presented in the Statement of Financial Condition	3,814	4,300
Gross Amounts Not Offset in the Statement of Financial Condition, Financial Instruments, Assets	1,215	2,149
Gross Amounts Not Offset in the Statement of Financial Condition, Cash Collateral Received, Assets	1,174	1,310
Net Amount, Assets	1,425	841
Gross and Net Amounts of Liabilities Presented in the Statement of Financial Condition	14,475	15,016
Gross Amount Not Offset in the Statement of Financial Condition, Financial Instruments, Liabilities	1,215	2,149
Gross Amounts Not Offset in the Statement of Financial Condition, Cash Collateral Pledged, Liabilities	12,909	12,076
Net Amount, Liabilities	351	791
Reverse Repurchase Agreements
Offsetting Assets and Liabilities [Line Items]
Gross and Net Amounts of Assets Presented in the Statement of Financial Condition	45,301	204,893
Gross Amounts Not Offset in the Statement of Financial Condition, Financial Instruments, Assets	45,151	203,938
Net Amount, Assets	150	955
Net Investment Hedges
Offsetting Assets and Liabilities [Line Items]
Gross and Net Amounts of Assets Presented in the Statement of Financial Condition	9	319
Gross Amounts Not Offset in the Statement of Financial Condition, Financial Instruments, Assets	9	1
Net Amount, Assets		318
Gross and Net Amounts of Liabilities Presented in the Statement of Financial Condition	1,677	1
Gross Amount Not Offset in the Statement of Financial Condition, Financial Instruments, Liabilities	9	$ 1
Net Amount, Liabilities	$ 1,668