Goodwill and Other Intangible Assets - Other Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	$ 130,767	$ 143,020
Accumulated Amortization	(84,131)	(93,849)
Valuation Allowance	(481)	(289)
Net Intangible Assets	46,155	48,882
Loan Servicing Rights
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	65,176	75,932
Accumulated Amortization	(48,934)	(59,251)
Valuation Allowance	(481)	(289)
Net Intangible Assets	15,761	16,392
Core Deposits
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	61,504	62,714
Accumulated Amortization	(33,406)	(31,934)
Valuation Allowance	0	0
Net Intangible Assets	28,098	30,780
Other
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	4,087	4,374
Accumulated Amortization	(1,791)	(2,664)
Valuation Allowance	0	0
Net Intangible Assets	$ 2,296	$ 1,710