Fair Value Measurements, Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis (Details) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Mortgage Servicing Rights (MSR) Impairment (Recovery)	$ (12,231)	$ 18,481
Mortgage servicing rights	50,373		$ 41,990
Equity securities	14,000		13,000
Investment securities gains (losses), net	17,939		15,106
Fair Value, Inputs, Level 3
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Equity securities	13,830		13,444
Investment securities gains (losses), net	13,830		13,444
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 2
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Write-down or Reserve, Amount	6,449		3,747
OREO(b)	21,847		6,125
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Individually evaluated loans(a)	78,139		138,752
Provision for credit losses	(4,227)		97,519
Mortgage Servicing Rights (MSR) Impairment (Recovery)	12,231		(17,704)
Mortgage servicing rights	$ 50,373		$ 41,990