Pending Acquisitions - Expenditures Related to Pending Acquisition (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Business Acquisition [Line Items]
Other	$ 36,886	$ 34,495	$ 115,744	$ 103,492
Total non-interest expense	151,823	144,450	457,395	429,026
Acquisition-related Costs [Member]
Business Acquisition [Line Items]
Professional Fees			853
Travel and Entertainment Expense			17
Other			3
Total non-interest expense			$ 873