Derivative Financial Instruments (Narrative) (Detail) (USD $)	9 Months Ended		9 Months Ended		9 Months Ended			1 Months Ended							3 Months Ended															3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Terminated forward-settle interest rate swap hedges [Member]	Sep. 30, 2013 Interest Rate Cap [Member]	Sep. 30, 2013 Current Derivative Credit Exposure [Member]	Sep. 30, 2013 Interest Rate Swaps With Bank Customers [Member] Current Derivative Credit Exposure [Member]	Sep. 30, 2013 Interest Rate Swaps With Bank Customers [Member] Future Derivative Credit Exposure [Member]	Mar. 31, 2010 Future [Member]	Mar. 31, 2013 Future [Member]	Sep. 30, 2012 Future [Member]	Sep. 30, 2011 Future [Member]	Mar. 30, 2010 Future [Member]	Sep. 30, 2013 Future [Member] Collateral pledged [Member]	Sep. 30, 2013 3 month LIBOR [Member] Interest rate swap on FHLB advances [Member]	Jun. 30, 2014 Scenario, Forecast [Member] Five Year Swaps [Member]	Jun. 30, 2014 Scenario, Forecast [Member] Ten Year Swaps [Member]	Sep. 30, 2013 Not Designated as Hedging Instrument [Member]	Dec. 31, 2012 Not Designated as Hedging Instrument [Member]	Sep. 30, 2013 Designated as Hedging Instrument [Member]	Dec. 31, 2012 Designated as Hedging Instrument [Member]	Sep. 26, 2013 Cash Flow Hedging [Member] Designated as Hedging Instrument [Member] Forward Contracts [Member]	Sep. 10, 2013 Cash Flow Hedging [Member] Designated as Hedging Instrument [Member] Forward Contracts [Member] Derivative	Sep. 30, 2013 Other Assets [Member] Not Designated as Hedging Instrument [Member] Mortgage Banking Derivatives [Member]	Dec. 31, 2012 Other Assets [Member] Not Designated as Hedging Instrument [Member] Mortgage Banking Derivatives [Member]	Sep. 30, 2013 Other Liabilities [Member] Cash Flow Hedging [Member] Designated as Hedging Instrument [Member] Forward Contracts [Member] Derivative	Dec. 31, 2012 Other Liabilities [Member] Cash Flow Hedging [Member] Designated as Hedging Instrument [Member] Forward Contracts [Member] Derivative	Sep. 30, 2013 Federal Home Loan Bank Advances [Member] Cash Flow Hedging [Member] Designated as Hedging Instrument [Member] Interest Rate Cap [Member] Derivative	Sep. 30, 2013 Federal Home Loan Bank Advances [Member] Other Assets [Member] Cash Flow Hedging [Member] Designated as Hedging Instrument [Member] Interest Rate Cap [Member] Derivative	Dec. 31, 2012 Federal Home Loan Bank Advances [Member] Other Assets [Member] Cash Flow Hedging [Member] Designated as Hedging Instrument [Member] Interest Rate Cap [Member] Derivative	Sep. 30, 2013 Other Expense [Member] Not Designated as Hedging Instrument [Member]	Sep. 30, 2012 Other Expense [Member] Not Designated as Hedging Instrument [Member]	Sep. 30, 2013 Other Expense [Member] Not Designated as Hedging Instrument [Member]	Sep. 30, 2012 Other Expense [Member] Not Designated as Hedging Instrument [Member]	Sep. 30, 2013 Other Expense [Member] Not Designated as Hedging Instrument [Member] Forward Contracts [Member]	Sep. 30, 2012 Other Expense [Member] Not Designated as Hedging Instrument [Member] Forward Contracts [Member]	Sep. 30, 2013 Other Expense [Member] Not Designated as Hedging Instrument [Member] Forward Contracts [Member]	Sep. 30, 2012 Other Expense [Member] Not Designated as Hedging Instrument [Member] Forward Contracts [Member]	Sep. 30, 2013 Other Expense [Member] Not Designated as Hedging Instrument [Member] Future [Member]	Sep. 30, 2012 Other Expense [Member] Not Designated as Hedging Instrument [Member] Future [Member]	Sep. 30, 2013 Other Expense [Member] Not Designated as Hedging Instrument [Member] Future [Member]	Sep. 30, 2012 Other Expense [Member] Not Designated as Hedging Instrument [Member] Future [Member]	Sep. 30, 2013 Customer Position [Member] Not Designated as Hedging Instrument [Member] Derivative	Dec. 31, 2012 Customer Position [Member] Not Designated as Hedging Instrument [Member] Derivative	Sep. 30, 2013 Customer Position [Member] Other Assets [Member] Not Designated as Hedging Instrument [Member] Derivative	Dec. 31, 2012 Customer Position [Member] Other Assets [Member] Not Designated as Hedging Instrument [Member] Derivative	Sep. 30, 2013 Customer Position [Member] Other Liabilities [Member] Not Designated as Hedging Instrument [Member] Derivative	Dec. 31, 2012 Customer Position [Member] Other Liabilities [Member] Not Designated as Hedging Instrument [Member] Derivative	Sep. 30, 2013 Initial [Member]	Sep. 30, 2013 Variation [Member]
Derivative [Line Items]
Cash Collateral Posted	$ 16,165,000	$ 42,770,000																																														$ 4,600,000	$ 16,800,000
Cash Collateral (Received)																																																	5,300,000
Number of Instruments																					2	4			4	4	2	2	0													219	201	153	178	66	23
Derivative Asset, Notional Amount																											25,000,000	50,000,000	0
Derivative Liability, Notional Amount																					25,000,000	25,000,000			100,000,000	100,000,000
Notional Amount	1,581,951,000	1,403,512,000							800,000,000		400,000,000	600,000,000																														1,382,011,000	1,203,569,000	820,055,000	1,009,623,000	561,956,000	193,946,000
Derivative period								1 year							5 years	10 years
Unamortized loss on termination of cash flow hedges			34,500,000
Estimate to be reclassified from OCI to interest expense			8,100,000		1,500,000
Total Outstanding				150,000,000
Strike rate														3.00%
Fair value gain				1,100,000
Premium paid				2,000,000
Hedge accounting adjustments	1,865,000	4,470,000
Cash collateral													634,000
Maximum exposure						33,000,000	9,900,000
Fair value of contracts										187,000																																8,379,000	124,000			8,379,000	124,000
Net impact on interest expense on borrowings																														1,061,000	1,222,000	2,854,000	3,744,000	(450,000)	(229,000)	(290,000)	(12,000)	(450,000)	(229,000)	(290,000)	(12,000)
Outstanding rate locks	59,900,000
Outstanding commitments to sell residential mortgage loans	88,300,000
Mandatory forward commitments	86,900,000
MTM Gain																	$ 12,846,000	$ 544,000	$ 3,047,000	$ 0			$ (400,000)	$ 2,900,000																		$ 33,028,000	$ 50,969,000	$ 33,028,000	$ 50,969,000