Fair Values of Assets and Liabilities (Summary of Changes in Level 3 Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Mortgage loans held-for-sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 48,655	$ 0
Net income	466	0
Other comprehensive income or loss	0	0
Purchases	0	0
Issuances	0	0
Sales	0	0
Settlements	(18,619)	0
Net transfers into Level 3	13,748	0
Ending balance	44,250	0
Loans held-for- investment
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	84,165	15,891
Net income	364	(772)
Other comprehensive income or loss	0	0
Purchases	0	0
Issuances	0	0
Sales	0	0
Settlements	(20,322)	(1,667)
Net transfers into Level 3	5,286	31,012
Ending balance	69,493	44,464
Mortgage servicing rights
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	230,225	147,571
Net income	(5,755)	51,575
Other comprehensive income or loss	0	0
Purchases	0	0
Issuances	0	0
Sales	0	0
Settlements	0	0
Net transfers into Level 3	0	0
Ending balance	224,470	199,146
Derivative assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	1,711	10,560
Net income	3,645	(7,113)
Other comprehensive income or loss	0	0
Purchases	0	0
Issuances	0	0
Sales	0	0
Settlements	0	0
Net transfers into Level 3	0	0
Ending balance	5,356	3,447
Municipal securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	117,537	105,687
Net income	0	0
Other comprehensive income or loss	(1,662)	(5,449)
Purchases	4,418	1,246
Issuances	0	0
Sales	0	0
Settlements	(8,036)	(1,083)
Net transfers into Level 3	0	0
Ending balance	112,257	100,401
U.S. government agencies
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	0	0
Net income	0	0
Other comprehensive income or loss	0	0
Purchases	0	0
Issuances	0	0
Sales	0	0
Settlements	0	0
Net transfers into Level 3	0	0
Ending balance	$ 0	$ 0