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		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Mortgage loans held-for-sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 44,250	$ 0	$ 48,655	$ 0
Net income	402	(2,900)	868	(2,900)
Other comprehensive income or loss	0	0	0	0
Purchases	0	0	0	0
Issuances	0	0	0	0
Sales	0	0	0	0
Settlements	(23,973)	0	(42,592)	0
Net transfers into Level 3	8,727	91,863	22,475	91,863
Ending balance	29,406	88,963	29,406	88,963
Loans held-for- investment
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	69,493	44,464	84,165	15,891
Net income	(619)	(1,775)	(255)	(2,547)
Other comprehensive income or loss	0	0	0	0
Purchases	0	0	0	0
Issuances	0	0	0	0
Sales	0	0	0	0
Settlements	(16,593)	(7,231)	(36,915)	(8,898)
Net transfers into Level 3	8,842	49,340	14,128	80,352
Ending balance	61,123	84,798	61,123	84,798
Mortgage servicing rights
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	224,470	199,146	230,225	147,571
Net income	6,392	13,518	637	65,093
Other comprehensive income or loss	0	0	0	0
Purchases	0	0	0	0
Issuances	0	0	0	0
Sales	(30,170)	0	(30,170)	0
Settlements	0	0	0	0
Net transfers into Level 3	0	0	0	0
Ending balance	200,692	212,664	200,692	212,664
Derivative assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	5,356	3,447	1,711	10,560
Net income	(1,869)	3,202	1,776	(3,911)
Other comprehensive income or loss	0	0	0	0
Purchases	0	0	0	0
Issuances	0	0	0	0
Sales	0	0	0	0
Settlements	0	0	0	0
Net transfers into Level 3	0	0	0	0
Ending balance	3,487	6,649	3,487	6,649
Municipal securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	112,257	100,401	117,537	105,687
Net income	0	0	0	0
Other comprehensive income or loss	(3,161)	(685)	(4,823)	(6,134)
Purchases	6,978	15,497	11,396	16,743
Issuances	0	0	0	0
Sales	0	0	0	0
Settlements	(1,919)	(1,728)	(9,955)	(2,811)
Net transfers into Level 3	0	0	0	0
Ending balance	$ 114,155	$ 113,485	$ 114,155	$ 113,485