Fair Value Measurements - Valuation and Inputs, at FV (Details) $ in Thousands	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Recurring
Fair value inputs, quantitative information
Asset, fair value	$ 610,228	$ 399,176
Liabilities, fair value	11,604	5,250
Recurring | Level 3 inputs
Fair value inputs, quantitative information
Asset, fair value	207,060	114,660
Assets valued using quoted or transaction prices in which quantitative unobservable inputs are not developed	113,900	20,700
Loans, held at fair value
Fair value inputs, quantitative information
Assets valued using quoted or transaction prices in which quantitative unobservable inputs are not developed	88,726	20,212	$ 22,664
Mortgage backed securities
Fair value inputs, quantitative information
Assets valued using quoted or transaction prices in which quantitative unobservable inputs are not developed	25,131	460	12,148
Mortgage servicing rights
Fair value inputs, quantitative information
Assets valued using quoted or transaction prices in which quantitative unobservable inputs are not developed	76,840	91,174	$ 93,065
Mortgage servicing rights | Recurring | Level 3 inputs
Fair value inputs, quantitative information
Asset, fair value	$ 76,840	91,174
Servicing Asset, Valuation Technique [Extensible List]	us-gaap:ValuationTechniqueDiscountedCashFlowMember
Mortgage servicing rights | Recurring | Level 3 inputs | Discounted Cash Flow
Fair value inputs, quantitative information
Servicing Asset, Valuation Technique [Extensible List]	us-gaap:ValuationTechniqueDiscountedCashFlowMember
Derivative instruments | Recurring | Level 3 inputs | Market Approach
Fair value inputs, quantitative information
Asset, fair value	$ 16,363	$ 2,814
Derivative instruments | Recurring | Level 3 inputs | Origination Pull-Through Rate | Minimum
Fair value inputs, quantitative information
Derivative Asset, Measurement Input	0.4762	0.4800
Derivative instruments | Recurring | Level 3 inputs | Origination Pull-Through Rate | Maximum
Fair value inputs, quantitative information
Derivative Asset, Measurement Input	1	1
Derivative instruments | Recurring | Level 3 inputs | Origination Pull-Through Rate | Weighted Average
Fair value inputs, quantitative information
Derivative Asset, Measurement Input	0.841	0.841
Derivative instruments | Recurring | Level 3 inputs | Servicing Fee Multiple | Minimum
Fair value inputs, quantitative information
Derivative Asset, Measurement Input	0.0051	0.0035
Derivative instruments | Recurring | Level 3 inputs | Servicing Fee Multiple | Maximum
Fair value inputs, quantitative information
Derivative Asset, Measurement Input	0.128	0.080
Derivative instruments | Recurring | Level 3 inputs | Servicing Fee Multiple | Weighted Average
Fair value inputs, quantitative information
Derivative Asset, Measurement Input	0.036	0.052
Derivative instruments | Recurring | Level 3 inputs | Percentage of Unpaid Principal Balance | Minimum
Fair value inputs, quantitative information
Derivative Asset, Measurement Input	0.0013	0.0009
Derivative instruments | Recurring | Level 3 inputs | Percentage of Unpaid Principal Balance | Maximum
Fair value inputs, quantitative information
Derivative Asset, Measurement Input	0.029	0.033
Derivative instruments | Recurring | Level 3 inputs | Percentage of Unpaid Principal Balance | Weighted Average
Fair value inputs, quantitative information
Derivative Asset, Measurement Input	0.011	0.017