Goodwill and Other Intangible Assets - Other Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	$ 110,316	$ 104,449
Accumulated Amortization	(70,314)	(70,280)
Valuation Allowance	(1,000)	(3,046)
Net Intangible Assets	39,002	31,123
Loan servicing rights [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	69,244	63,377
Accumulated Amortization	(41,485)	(43,393)
Valuation Allowance	(1,000)	(3,046)
Net Intangible Assets	26,759	16,938
Core deposits [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	35,194	35,194
Accumulated Amortization	(25,805)	(24,160)
Valuation Allowance
Net Intangible Assets	9,389	11,034
Other [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	5,878	5,878
Accumulated Amortization	(3,024)	(2,727)
Valuation Allowance
Net Intangible Assets	$ 2,854	$ 3,151