Derivative Financial Instruments (Narrative) (Detail) (USD $)	3 Months Ended		6 Months Ended			6 Months Ended	0 Months Ended	6 Months Ended	0 Months Ended						6 Months Ended		0 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Jun. 30, 2013 Forward Settle Interest Rate Swap Hedges Which Qualify For Cash Flow Hedge Accounting [Member]	Jul. 02, 2012 Forward Settle Interest Rate Swap Hedges Which Qualify For Cash Flow Hedge Accounting [Member] Five Year Swaps [Member] Derivative	Jun. 30, 2013 Forward Settle Interest Rate Swap Hedges Which Qualify For Cash Flow Hedge Accounting [Member] Five Year Swaps [Member]	Mar. 26, 2012 Forward Settle Interest Rate Swap Hedges Which Qualify For Cash Flow Hedge Accounting [Member] Terminated Forward Settle Interest Rate Swap [Member]	Mar. 21, 2012 Forward Settle Interest Rate Swap Hedges Which Qualify For Cash Flow Hedge Accounting [Member] Terminated Forward Settle Interest Rate Swap [Member]	Jun. 02, 2012 Forward Settle Interest Rate Swap Number One [Member] Five Year Swaps [Member]	May 02, 2012 Forward Settle Interest Rate Swap Number One [Member] Five Year Swaps [Member]	Dec. 07, 2012 Forward Settle Interest Rate Swap Number Two [Member]	Nov. 30, 2012 Forward Settle Interest Rate Swap Number Two [Member]	Jun. 30, 2013 Interest Rate Swaps On FHLB Advances [Member]	Dec. 31, 2012 Interest Rate Swaps On FHLB Advances [Member]	Apr. 30, 2010 Interest Rate Swaps On FHLB Advances [Member] 3-Month LIBOR Indexed Floating Rate FHLB Advance Maturing April 29, 2013 [Member] Derivative	Apr. 02, 2010 Interest Rate Swaps On FHLB Advances [Member] 3-Month LIBOR Indexed Floating Rate FHLB Advance Maturing April 29, 2013 [Member]	Jun. 30, 2013 Interest Rate Swaps On FHLB Advances [Member] 3-Month LIBOR Indexed Floating Rate FHLB Advance Maturing April 29, 2013 [Member]	Apr. 30, 2010 Interest Rate Swaps on FHLP Advances Two [Member] 3-Month LIBOR Indexed Floating Rate FHLB Advance Maturing April 29, 2013 [Member]	Mar. 30, 2010 Future [Member]	Jun. 30, 2013 September 2011 Through April 2013 Futures Contracts [Member]	Jul. 02, 2012 September 2011 Through April 2013 Futures Contracts [Member]	Jun. 30, 2013 Interest Rate Locked Loan And Forward Sales Commitments [Member]	Dec. 31, 2012 Interest Rate Locked Loan And Forward Sales Commitments [Member]	Jun. 30, 2013 Current Derivative Credit Exposure [Member] Interest Rate Swaps With Bank Customers [Member]	Jun. 30, 2013 Future Derivative Credit Exposure [Member] Interest Rate Swaps With Bank Customers [Member]	Jun. 30, 2013 Collateral pledged [Member]	Jun. 30, 2013 Collateral pledged [Member] Future [Member]	Jun. 30, 2013 Collateral received [Member]
Derivative [Line Items]
Cash Collateral for Borrowed Securities																												$ 11,300,000	$ 580,000	$ 7,000,000
Number of forward settle interest rate swap hedges entered							2										2
Notional Outstanding	1,340,819,000		1,340,819,000		1,403,512,000	100,000,000	25,000,000								0	100,000,000	25,000,000			150,000,000	600,000,000	800,000,000	400,000,000
Cash settlement								5 years
Derivative, Cap Interest Rate	3.00%		3.00%
Unamortized Gain On Termination Of Cash Flow Hedges	900,000		900,000
Derivative, maturity date							Jul. 02, 2018		Mar. 28, 2016	Mar. 21, 2016	Mar. 28, 2018	Mar. 28, 2018	Dec. 07, 2018	Nov. 30, 2018				Apr. 29, 2013
Interest rate swap, base rate						1-month LIBOR									3-month LIBOR
Amount to be reclassified as increase to interest expense			8,600,000
Valuation balance recorded in other comprehensive income related to cash flow hedge																			1,100,000
Maximum Potential Future Exposure on Credit Risk Derivatives																										30,700,000	9,300,000
Unamortized loss on the termination of cash flow hedges	36,700,000		36,700,000
Unamortized gain on the termination of fair value hedges	2,700,000		2,700,000
Fair value of contracts		141,000		141,000
Future contracts, recognized mark to market gain	108,000	61,000	160,000	217,000
Outstanding rate locks	129,300,000		129,300,000
Outstanding commitments to sell residential mortgage loans	172,600,000		172,600,000
Mandatory forward commitments			167,300,000
Commitments, fair value																								5,100,000	2,900,000
Unamortized Premium On Cash Flow Hedges																			$ 1,960,000