Acquisitions - Loans at Acquisition Date (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 04, 2011
Loans At Acquisition Date [Line Items]
Acquired Impaired	$ 535,489
Acquired Performing	5,911,353
Total Acquired Loans	6,446,842
Commercial Non-Real Estate [Member]
Loans At Acquisition Date [Line Items]
Acquired Impaired	128,813
Acquired Performing	2,414,002
Total Acquired Loans	2,542,815
Commercial Real Estate Owner-Occupied [Member]
Loans At Acquisition Date [Line Items]
Acquired Impaired	91,885
Acquired Performing	856,583
Total Acquired Loans	948,468
Construction and Land Development [Member]
Loans At Acquisition Date [Line Items]
Acquired Impaired	159,438
Acquired Performing	564,795
Total Acquired Loans	724,233
Commercial Real Estate Non-Owner Occupied [Member]
Loans At Acquisition Date [Line Items]
Acquired Impaired	86,573
Acquired Performing	839,258
Total Acquired Loans	925,831
Commercial/Real Estate [Member]
Loans At Acquisition Date [Line Items]
Acquired Impaired	466,709
Acquired Performing	4,674,638
Total Acquired Loans	5,141,347
Residential mortgage loans [Member]
Loans At Acquisition Date [Line Items]
Acquired Impaired	68,780
Acquired Performing	818,152
Total Acquired Loans	886,932
Consumer loans [Member]
Loans At Acquisition Date [Line Items]
Acquired Performing	418,563
Total Acquired Loans	$ 418,563