Derivative Financial Instruments (Schedule of Amounts Related to Interest Rate Derivatives Included in Income Designated as Hedges of Cash Flows) (Detail) - Designated as Hedging Instrument [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Interest Rate Swap On Junior Subordinated Deferrable Interest Debentures [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in other comprehensive income	$ 0	$ 0	$ (49)
Interest Income on Loans [Member] | Interest Rate Swaps On Variable-Rate Loans [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount reclassified from accumulated other comprehensive income to interest	0	30,604	37,380
Interest Expense [Member] | Interest Rate Swap On Junior Subordinated Deferrable Interest Debentures [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount reclassified from accumulated other comprehensive income to interest	$ 0	$ 0	$ 4,064