Fair Value Measurements - Financial Instruments Carried at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Assets:
Loans, held for sale, at fair value	$ 340,288	$ 188,077
Derivative instruments, at fair value	16,363	2,814
Residential mortgage servicing rights, at fair value	76,840	91,174
Liabilities:
Derivative instruments, at fair value	11,604	5,250
Recurring
Assets:
Loans, held for sale, at fair value	340,288	192,510
Loans, net at fair value	88,726	20,212
Mortgage backed securities, at fair value	88,011	92,466
Derivative instruments, at fair value	16,363	2,814
Residential mortgage servicing rights, at fair value	76,840	91,174
Total assets	610,228	399,176
Liabilities:
Derivative instruments, at fair value	11,604	5,250
Total liabilities	11,604	5,250
Recurring | Level 2 inputs
Assets:
Loans, held for sale, at fair value	340,288	192,510
Mortgage backed securities, at fair value	62,880	92,006
Total assets	403,168	284,516
Liabilities:
Derivative instruments, at fair value	11,604	5,250
Total liabilities	11,604	5,250
Recurring | Level 3 inputs
Assets:
Loans, net at fair value	88,726	20,212
Mortgage backed securities, at fair value	25,131	460
Derivative instruments, at fair value	16,363	2,814
Residential mortgage servicing rights, at fair value	76,840	91,174
Total assets	$ 207,060	$ 114,660