Significant Accounting Policies - (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Significant Accounting Policies
Mortgage servicing rights, at fair value	$ 3,878,078	$ 2,581,174
Income taxes payable	685,262	622,700
Stockholders' equity	$ 3,418,325	$ 3,389,388	$ 2,061,507	$ 1,653,791