Fair Value Measurements - Financial Instruments Carried at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Assets:
Loans, held for sale, at fair value	$ 297,669	$ 188,077
Derivative instruments, at fair value	19,037	2,814
Residential mortgage servicing rights, at fair value	73,645	91,174
Liabilities:
Derivative instruments, at fair value	9,106	5,250
Recurring
Assets:
Loans, held for sale, at fair value	301,304	192,510
Loans, net at fair value	124,298	20,212
Mortgage backed securities, at fair value	75,411	92,466
Derivative instruments, at fair value	19,037	2,814
Residential mortgage servicing rights, at fair value	73,645	91,174
Total assets	593,695	399,176
Liabilities:
Derivative instruments, at fair value	9,106	5,250
Total liabilities	9,106	5,250
Recurring | Level 2 inputs
Assets:
Loans, held for sale, at fair value	301,304	192,510
Mortgage backed securities, at fair value	75,000	92,006
Total assets	376,304	284,516
Liabilities:
Derivative instruments, at fair value	9,106	5,250
Total liabilities	9,106	5,250
Recurring | Level 3 inputs
Assets:
Loans, net at fair value	124,298	20,212
Mortgage backed securities, at fair value	411	460
Derivative instruments, at fair value	19,037	2,814
Residential mortgage servicing rights, at fair value	73,645	91,174
Total assets	$ 217,391	$ 114,660