Loans and Leases (Schedule of Changes in Accretable Discount Related to Credit Impaired Acquired Loans) (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Changes In Accretable Discount [Line Items]
Balance - beginning of period	$ 49,187,000	$ 50,527,000	$ 62,868,000	$ 4,881,000
Accretion to interest income	(4,229,000)	(4,902,000)	(16,522,000)	(13,674,000)
Net reclassification to non-accretable from accretable	1,481,000	12,299,000	93,000	12,299,000
Balance - end of period	46,439,000	57,924,000	46,439,000	57,924,000
Tower [Member]
Changes In Accretable Discount [Line Items]
Tower acquisition	$ 0	$ 0	$ 0	$ 54,418,000