Goodwill and Other Intangible Assets - Other Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	$ 172,972	$ 171,769
Accumulated Amortization	(99,285)	(94,696)
Valuation Allowance	(107)	(83)
Net Intangible Assets	73,580	76,990
Loan servicing rights
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	88,557	87,354
Accumulated Amortization	(64,939)	(63,161)
Valuation Allowance	(107)	(83)
Net Intangible Assets	23,511	24,110
Core deposits
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	80,470	80,470
Accumulated Amortization	(31,888)	(29,136)
Valuation Allowance	0	0
Net Intangible Assets	48,582	51,334
Other
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	3,945	3,945
Accumulated Amortization	(2,458)	(2,399)
Valuation Allowance	0	0
Net Intangible Assets	$ 1,487	$ 1,546