Mortgage Banking - Capitalized Mortgage and Valuation Allowance (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Mortgage servicing assets:
Balance at beginning of period	$ 10,801	$ 10,419
Loans sold, servicing retained	1,376	278
Mortgage servicing rights acquired	9,747
Amortization	(1,163)	(286)
Carrying value before valuation allowance at end of period	20,761	10,411
Valuation allowance:
Balance at beginning of period	(534)	(300)
Impairment recovery (charges)	(4,485)	(113)
Balance at end of period	(5,019)	(413)
Net carrying value of MSRs at end of period	15,742	9,998
Fair value of MSRs at end of period	$ 16,105	$ 10,264