Derivative Instruments and Hedging Activities - Summary of Offsetting of Financial Assets and Derivative Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Offsetting Assets [Line Items]
Net Amounts of Assets Presented in the Consolidated Balance Sheet	$ 10,938	$ 7,552
Interest Rate Swaps
Offsetting Assets [Line Items]
Gross Amount of Recognized Assets	0	192
Gross Amounts Offset in the Consolidated Balance Sheet	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheet	0	192
Gross amounts not offset in the consolidated balance sheet, Financial instruments	0	192
Gross amounts not offset in the consolidated balance sheet, Cash collateral received	0	0
Gross amounts not offset in the consolidated balance sheet, Net amount	$ 0	$ 0