Loans and Allowance for Credit Losses - Schedule of Composition of Loans (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Jun. 30, 2013	Sep. 30, 2012	Jul. 01, 2012	Dec. 31, 2011
Financing Receivable, Allowance for Credit Losses [Line Items]
Direct finance leases	$ 30,100	$ 57,700
Total loans	5,072,476	5,196,594		5,243,166
Allowance for loan losses	(42,306)	(49,047)		(50,428)
Allowance for loan losses-covered loans	(5,012)	(5,716)
Net loans	5,025,158	5,141,831		5,188,404
Commercial Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Direct finance leases	1,381,216	1,336,820
Total loans	1,416,520	1,392,459
Allowance for loan losses	(14,520)	(14,642)	(15,084)	(17,966)	(17,850)	(19,964)
Commercial Real Estate-Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Direct finance leases	83,205	99,081
Commercial Real Estate-Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Direct finance leases	1,082,561	1,156,802
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Direct finance leases	1,344,350	1,324,703
Consumer Credit Heloc [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Direct finance leases	249,013	258,114
Consumer Loans Auto Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Direct finance leases	585,285	526,085
Consumer Credit Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Direct finance leases	96,045	122,656
Covered Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Direct finance leases	$ 250,801	$ 372,333