Mortgage Servicing Rights Summary of Changes in Mortgage Servicing Rights (Details) - Mortgage - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Amortized cost:
Balance at beginning of year	$ 37,663	$ 38,822
Originations of mortgage servicing rights	6,756	4,968
Amortization expense	(5,846)	(6,127)
Balance at end of year	38,573	37,663
Valuation allowance:
Balance at beginning of year	0	(1,291)
Net deductions to the valuation allowance	0	1,291
Balance at end of year	0	0
Net MSRs at end of year	38,573	$ 37,663
Amortization [Abstract]
2019	6,477
2020	6,037
2021	5,549
2022	5,010
2023	$ 4,419

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Amortized amount of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

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