Mortgage Servicing Rights ("MSRs") (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Servicing Asset at Fair Value, Amount [Roll Forward]
Balance at beginning of the period	$ 127,604	$ 77,203	$ 92,081	$ 85,638
Additions from loans sold with servicing retained	15,546	20,936	57,674	50,734
Estimate of changes in fair value due to:
Early buyout options (“EBO”) exercised	(116)	(367)	(518)	(367)
Payoffs and paydowns	(8,594)	(7,863)	(27,302)	(23,557)
Changes in valuation inputs or assumptions	(888)	(3,002)	11,617	(25,541)
Fair value at end of the period	133,552	86,907	133,552	86,907
Unpaid principal balance of mortgage loans serviced for others	$ 12,720,126	$ 10,139,878	$ 12,720,126	$ 10,139,878