Fair Value Measurement and Fair Value of Financial Instruments (Increase (Decrease) in Fair Value of Assets Measured on a Nonrecurring Basis) (Details) - Fair Value, Measurements, Nonrecurring - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Non-PCI impaired loans
Fair Value, Assets Measured on a Nonrecurring Basis
Increase (decrease) in value of assets		$ (2,810)
Impaired loans
Fair Value, Assets Measured on a Nonrecurring Basis
Increase (decrease) in value of assets	$ (19,208)
Investments in tax credit and other investments, net
Fair Value, Assets Measured on a Nonrecurring Basis
Increase (decrease) in value of assets	150	(6,978)
Other nonperforming assets
Fair Value, Assets Measured on a Nonrecurring Basis
Increase (decrease) in value of assets	(300)	0
Commercial lending | Non-PCI impaired loans
Fair Value, Assets Measured on a Nonrecurring Basis
Increase (decrease) in value of assets		(2,732)
Commercial lending | Impaired loans
Fair Value, Assets Measured on a Nonrecurring Basis
Increase (decrease) in value of assets	(21,506)
Commercial lending | Commercial and industrial (“C&I”) | Non-PCI impaired loans
Fair Value, Assets Measured on a Nonrecurring Basis
Increase (decrease) in value of assets		(2,734)
Commercial lending | Commercial and industrial (“C&I”) | Impaired loans
Fair Value, Assets Measured on a Nonrecurring Basis
Increase (decrease) in value of assets	(21,501)
Commercial lending | Commercial real estate (“CRE”) | Non-PCI impaired loans
Fair Value, Assets Measured on a Nonrecurring Basis
Increase (decrease) in value of assets		2
Commercial lending | Commercial real estate (“CRE”) | Impaired loans
Fair Value, Assets Measured on a Nonrecurring Basis
Increase (decrease) in value of assets	(5)
Consumer lending | Non-PCI impaired loans
Fair Value, Assets Measured on a Nonrecurring Basis
Increase (decrease) in value of assets		(78)
Consumer lending | Impaired loans
Fair Value, Assets Measured on a Nonrecurring Basis
Increase (decrease) in value of assets	2,298
Consumer lending | HELOCs | Non-PCI impaired loans
Fair Value, Assets Measured on a Nonrecurring Basis
Increase (decrease) in value of assets		(78)
Consumer lending | HELOCs | Impaired loans
Fair Value, Assets Measured on a Nonrecurring Basis
Increase (decrease) in value of assets	(193)
Consumer lending | Other consumer | Non-PCI impaired loans
Fair Value, Assets Measured on a Nonrecurring Basis
Increase (decrease) in value of assets		$ 0
Consumer lending | Other consumer | Impaired loans
Fair Value, Assets Measured on a Nonrecurring Basis
Increase (decrease) in value of assets	$ 2,491