Derivative Financial Instruments Schedule of the increase/(reduction) to interest expenses on borrowings related to cash flow hedges (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Derivative [Line Items]
Interest Expense	$ 22,544	$ 21,766	$ 67,397	$ 69,085
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Interest Expense	188	0	188	498
Amount Reclassified From AOCI	1,853	2,182	6,189	7,090
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Interest rate swaps on FHLB advances [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Interest Expense	188	0	188	498
Amount Reclassified From AOCI	1,355	1,353	4,060	4,604
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Interest rate swaps on senior fixed-rate notes [Member]
Derivative [Line Items]
Interest Expense	0	0	0	0
Amount Reclassified From AOCI	76		191
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Interest rate swaps on senior fixed-rate notes [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Amount Reclassified From AOCI		0		0
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Interest rate swaps on junior subordinated debt [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Interest Expense	0	0	0	0
Amount Reclassified From AOCI	0	0	0	(3)
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Interest rate swaps on repurchase agreements [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Interest Expense	0	0	0	0
Amount Reclassified From AOCI	361	829	1,864	2,489
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Bank Time Deposits [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Interest Expense	0	0	0	0
Amount Reclassified From AOCI	$ 61	$ 0	$ 74	$ 0