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, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Mortgage loans held-for-sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 0	$ 0	$ 0	$ 0
Net income	(2,900)	0	(2,900)	0
Other comprehensive income (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/(out of) Level 3	91,863	0	91,863	0
Ending balance	88,963	0	88,963	0
Loans held-for- investment
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	44,464	6,408	15,891	10,280
Net income	(1,775)	167	(2,547)	(363)
Other comprehensive income (loss)	0	0	0	0
Purchases	0	0	0	0
Issuances	0	0	0	0
Sales	0	0	0	0
Settlements	(7,231)	(59)	(8,898)	(3,977)
Net transfers into/(out of) Level 3	49,340	4,491	80,352	5,067
Ending balance	84,798	11,007	84,798	11,007
Mortgage servicing rights
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	199,146	124,316	147,571	92,081
Net income	13,518	3,288	65,093	35,523
Other comprehensive income (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/(out of) Level 3	0	0	0	0
Ending balance	212,664	127,604	212,664	127,604
Derivative assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	3,447	25,634	10,560	48,091
Net income	3,202	(3,064)	(3,911)	(25,521)
Other comprehensive income (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/(out of) Level 3	0	0	0	0
Ending balance	6,649	22,570	6,649	22,570
Municipal securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	100,401	101,748	105,687	109,876
Net income	0	0	0	0
Other comprehensive income (loss)	(685)	(374)	(6,134)	(2,442)
Purchases	15,497	18,163	16,743	18,163
Issuances	0	0	0	0
Sales	0	0	0	0
Settlements	(1,728)	(1,931)	(2,811)	(7,991)
Net transfers into/(out of) Level 3	0	0	0	0
Ending balance	113,485	117,606	113,485	117,606
U.S. government agencies
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	0	1,784	0	1,966
Net income	0	(4)	0	(4)
Other comprehensive income (loss)	0		0	(24)
Purchases	0	0	0	0
Issuances	0	0	0	0
Sales	0	0	0	0
Settlements	0	(1,780)	0	(1,938)
Net transfers into/(out of) Level 3	0	0	0	0
Ending balance	$ 0	$ 0	$ 0	$ 0