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		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Mortgage loans held-for-sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 88,963	$ 0	$ 0	$ 0
Net income	(787)	0	(3,687)	0
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	(27,512)	0	(27,512)	0
Net transfers (out of)/into Level 3	(12,244)	0	79,619	0
Ending balance	48,420	0	48,420	0
Loans held-for- investment
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	84,798	11,007	15,891	10,280
Net income	(1,574)	54	(4,121)	(309)
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	(12,986)	(588)	(21,884)	(4,565)
Net transfers (out of)/into Level 3	28,329	1,659	108,681	6,726
Ending balance	98,567	12,132	98,567	12,132
Mortgage servicing rights
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	212,664	127,604	147,571	92,081
Net income	17,007	5,948	82,100	41,471
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 (out of)/into Level 3	0	0	0	0
Ending balance	229,671	133,552	229,671	133,552
Derivative assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	6,649	22,570	10,560	48,091
Net income	(6,508)	(7,958)	(10,419)	(33,479)
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 (out of)/into Level 3	0	0	0	0
Ending balance	141	14,612	141	14,612
Municipal securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	113,485	117,606	105,687	109,876
Net income	0	0	0	0
Other comprehensive income or loss	(2,618)	(757)	(8,752)	(3,199)
Purchases	11,590	875	28,333	19,038
Issuances	0	0	0	0
Sales	0	0	0	0
Settlements	(25)	0	(2,836)	(7,991)
Net transfers (out of)/into Level 3	0	0	0	0
Ending balance	122,432	117,724	122,432	117,724
U.S. government agencies
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	0	0	0	1,966
Net income	0	0	0	(4)
Other comprehensive income or loss	0		0	(24)
Purchases	0	0	0	0
Issuances	0	0	0	0
Sales	0	0	0	0
Settlements	0	0	0	(1,938)
Net transfers (out of)/into Level 3	0	0	0	0
Ending balance	$ 0	$ 0	$ 0	$ 0