Loans Receivable - Schedule of Non-Covered Loans on Nonaccrual Status (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans on nonaccrual status	$ 46,565	$ 47,916
Residential Mortgage Loans [Member] | Mortgage - Prime [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans on nonaccrual status	8,159	8,367
Residential Mortgage Loans [Member] | Mortgage - Subprime [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans on nonaccrual status
Commercial Loans [Member] | Commercial Real Estate Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans on nonaccrual status	5,939	5,479
Commercial Loans [Member] | Commercial Real Estate - Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans on nonaccrual status	21,995	23,475
Commercial Loans [Member] | Business [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans on nonaccrual status	1,930	3,358
Consumer And Other Loans [Member] | Indirect Automobile [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans on nonaccrual status	982	868
Consumer And Other Loans [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans on nonaccrual status	6,808	5,635
Consumer And Other Loans [Member] | Credit Card [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans on nonaccrual status	403	424
Consumer And Other Loans [Member] | Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans on nonaccrual status	$ 349	$ 310