Supplemental Cash Flow Disclosures - Non-cash Investing and Financing Activities (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash paid during the year for:
Interest	$ 15,624,000	$ 33,964,000	$ 56,005,000
Income taxes	22,374,000	25,914,000	21,787,000
Non-cash investing and financing activities:
Real Estate Owned, Transfer to Real Estate Owned	3,163,000	3,865,000	4,723,000
Fair value of loans transferred from held to maturity to available for sale	73,697,000	37,305,000	30,359,000
Transfer of Loans Held-for-sale to Portfolio Loans	0	4,335,000	482,000
Gross (decrease) increase in market value adjustment to securities available for sale	(29,908,000)	19,911,000	20,604,000
Gross (decrease) increase in market value adjustment to derivatives	(3,356,000)	(4,467,000)	935,000
Investments Committed to Purchase, Not Yet Paid	0	(34,185,000)	25,484,000
Increase in Commitment to Limited Partnership	7,565,000	0	1,469,000
Noncash or Part Noncash Acquisition, Value of Liabilities Assumed	0	0	(361,595,000)
Other Significant Noncash Transaction, Consideration Received	0	(384,000)	484,000
Treasury stock reissued	$ 2,042,000	$ 1,594,000	$ 2,531,000