Financial Instruments with Off-Balance Sheet Risk and Derivatives (Company's Interest Rate Swaps) (Detail) - Swap - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Derivative [Line Items]
Notional Amount	$ 20,100,000	$ 20,900,000
Estimated Fair Value	$ 1,500,000	$ 1,500,000