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, 2018	Mar. 31, 2017
Non-PCI impaired loans
Fair Value, Assets Measured on a Nonrecurring Basis
Fair value adjustments of assets	$ 13,979	$ 49
OREO
Fair Value, Assets Measured on a Nonrecurring Basis
Fair value adjustments of assets	0	(285)
Commercial lending | Commercial and industrial (“C&I”) | Non-PCI impaired loans
Fair Value, Assets Measured on a Nonrecurring Basis
Fair value adjustments of assets	13,899	32
Commercial lending | Commercial real estate (“CRE”) | Non-PCI impaired loans
Fair Value, Assets Measured on a Nonrecurring Basis
Fair value adjustments of assets	95	(64)
Consumer lending | Real estate loan | Single-family | Non-PCI impaired loans
Fair Value, Assets Measured on a Nonrecurring Basis
Fair value adjustments of assets	(15)	82
Consumer lending | Other consumer | Non-PCI impaired loans
Fair Value, Assets Measured on a Nonrecurring Basis
Fair value adjustments of assets	$ 0	$ (1)