Goodwill and Other Intangible Assets - Other Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	$ 124,555	$ 138,593
Accumulated Amortization	(80,979)	(92,209)
Valuation Allowance	(715)	(900)
Net Intangible Assets	42,861	45,484
Loan servicing rights
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	77,072	73,002
Accumulated Amortization	(55,613)	(52,634)
Valuation Allowance	(715)	(900)
Net Intangible Assets	20,744	19,468
Core deposits
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	43,396	61,504
Accumulated Amortization	(23,142)	(37,562)
Valuation Allowance	0	0
Net Intangible Assets	20,254	23,942
Other
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	4,087	4,087
Accumulated Amortization	(2,224)	(2,013)
Valuation Allowance	0	0
Net Intangible Assets	$ 1,863	$ 2,074