Derivative and Hedging Activities - Offsetting of Derivative Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Gross Amount	$ 108,149	$ 53,202
Gross Amounts Offset in the Balance Sheet, Derivative Assets	0	0
Net Amount Presented in the Balance Sheet	108,149	53,202
Credit Risk Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Amount	47	7
Gross Amounts Offset in the Balance Sheet, Derivative Assets	0	0
Net Amount Presented in the Balance Sheet	47	7
Subject to Master Netting Arrangement [Member]
Derivatives, Fair Value [Line Items]
Net Amount Presented in the Balance Sheet	10,081	3,197
Subject to Master Netting Arrangement [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Amount	10,022	3,178
Gross Amounts Offset in the Balance Sheet, Derivative Assets	0	0
Net Amount Presented in the Balance Sheet	10,022	3,178
Subject to Master Netting Arrangement [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Gross Amount		1
Gross Amounts Offset in the Balance Sheet, Derivative Assets	0	0
Net Amount Presented in the Balance Sheet		1
Subject to Master Netting Arrangement [Member] | Equity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Amount	59	18
Gross Amounts Offset in the Balance Sheet, Derivative Assets	0	0
Net Amount Presented in the Balance Sheet	59	18
Not Subject to Master Netting Arrangement [Member]
Derivatives, Fair Value [Line Items]
Net Amount Presented in the Balance Sheet	98,068	50,005
Not Subject to Master Netting Arrangement [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Gross Amount	98,021	49,998
Gross Amounts Offset in the Balance Sheet, Derivative Assets	0	0
Net Amount Presented in the Balance Sheet	98,021	49,998
Not Subject to Master Netting Arrangement [Member] | Credit Risk Contracts [Member]
Derivatives, Fair Value [Line Items]
Net Amount Presented in the Balance Sheet	$ 47	$ 7