Derivative Instruments - Derivative Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Derivative [Line Items]
Net Amount Presented in the Balance Sheet	$ 51,605	$ 46,160
Subject to Master Netting Arrangement [Member]
Derivative [Line Items]
Net Amount Presented in the Balance Sheet	51,453	45,985
Gross Amount Not Offset in the Balance Sheet Financial Instruments, Derivative Liabilities	25,371	30,976
Gross Amount Not Offset in the Balance Sheet Cash Collateral Pledged, Derivative Liabilities	24,802	13,243
Net Amount, Derivative Liabilities	1,280	1,766
Subject to Master Netting Arrangement [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Net Amount Presented in the Balance Sheet	962	2,330
Gross Amount Not Offset in the Balance Sheet Financial Instruments, Derivative Liabilities	792	2,330
Gross Amount Not Offset in the Balance Sheet Cash Collateral Pledged, Derivative Liabilities	170
Subject to Master Netting Arrangement [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Net Amount Presented in the Balance Sheet	50,491	43,655
Gross Amount Not Offset in the Balance Sheet Financial Instruments, Derivative Liabilities	24,579	28,646
Gross Amount Not Offset in the Balance Sheet Cash Collateral Pledged, Derivative Liabilities	24,632	13,243
Net Amount, Derivative Liabilities	$ 1,280	$ 1,766