Fair Value Measurement and Fair Value of Financial Instruments (Fair Value Adjustments of Assets Measured on a Nonrecurring Basis) (Details) - Fair Value, Measurements, Nonrecurring - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Non-PCI impaired loans
Fair Value, Assets Measured on a Nonrecurring Basis
Fair value adjustments of assets	$ (2,810)	$ (13,979)
Impairment on tax credit investments
Fair Value, Assets Measured on a Nonrecurring Basis
Fair value adjustments of assets	(6,978)	0
Commercial lending | Commercial and industrial (“C&I”) | Non-PCI impaired loans
Fair Value, Assets Measured on a Nonrecurring Basis
Fair value adjustments of assets	(2,734)	(13,899)
Commercial lending | Commercial real estate (“CRE”) | Non-PCI impaired loans
Fair Value, Assets Measured on a Nonrecurring Basis
Fair value adjustments of assets	2	(95)
Consumer lending | Real estate loan | Single-family residential | Non-PCI impaired loans
Fair Value, Assets Measured on a Nonrecurring Basis
Fair value adjustments of assets	0	15
Consumer lending | HELOCs | Non-PCI impaired loans
Fair Value, Assets Measured on a Nonrecurring Basis
Fair value adjustments of assets	$ (78)	$ 0