Income Taxes (Deferred Tax Assets and Deferred Tax Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Allowance for loan losses	$ 192,534	$ 109,903
Investments in qualified affordable housing partnerships, tax credit and other investments, net	11,174	11,190
Deferred compensation	23,604	23,816
Interest income on nonaccrual loans	5,909	9,527
State taxes	273	5,848
Premises and equipment	2,096	1,578
Lease liability	30,554	35,948
Other	1,441	965
Total gross deferred tax assets	267,585	198,775
Valuation allowance	0	(21)
Total deferred tax assets, net of valuation allowance	267,585	198,754
Deferred tax liabilities:
Equipment lease financing	29,990	30,669
Investments in qualified affordable housing partnerships, tax credit and other investments, net	14,912	12,301
Core deposit intangibles	1,934	3,032
FHLB stock dividends	1,855	1,854
Mortgage servicing assets	1,675	1,839
Acquired debt	1,597	1,679
Prepaid expenses	1,194	1,100
Premises and equipment	99	1,890
Unrealized gains/losses on securities	21,593	890
Operating lease right-of-use assets	28,468	34,313
Other	453	2,700
Total gross deferred tax liabilities	103,770	92,267
Net deferred tax assets	$ 163,815	$ 106,487