Fair Value Measurement and Fair Value of Financial Instruments (Increase (Decrease) in Value of Assets Measured on a Nonrecurring Basis) (Details) - Fair Value, Measurements, Nonrecurring - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Non-PCI impaired loans
Fair Value, Assets Measured on a Nonrecurring Basis
Increase (decrease) in value of assets	$ (20,482)	$ (8,646)	$ (43,103)	$ (7,390)
OREO
Fair Value, Assets Measured on a Nonrecurring Basis
Increase (decrease) in value of assets	(1,020)	0	(1,023)	0
Investments in tax credit and other investments, net
Fair Value, Assets Measured on a Nonrecurring Basis
Increase (decrease) in value of assets	(1,703)	0	(11,573)	0
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	(20,484)	(8,508)	(43,109)	(7,204)
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	50	6	61
Consumer lending | Real estate loan | Single-family residential | Non-PCI impaired loans
Fair Value, Assets Measured on a Nonrecurring Basis
Increase (decrease) in value of assets	0	0	0	15
Consumer lending | HELOCs | Non-PCI impaired loans
Fair Value, Assets Measured on a Nonrecurring Basis
Increase (decrease) in value of assets	$ 0	$ (188)	$ 0	$ (262)