Investment Securities (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Oct. 06, 2015	Apr. 07, 2014
Schedule of Available-for-sale Securities [Line Items]
Available For Sale Securities Pledged As Collateral Amortized Cost	$ 425,500
Proceeds from sales of securities available-for-sale	393,509	$ 1,035,926	$ 465,608
Available-for-sale Securities, Gross Realized Gains	11,100	4,500	4,800
Available-for-sale Securities, Gross Realized Losses	1,600	700
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Reclassification Adjustments, Net of Tax	(16,244)	3,621	32,601
Federal Home Loan Bank stock, at cost	$ 21,870	$ 19,710
Federal Home Loan Bank Minimum Stock Ownership As Percent Of Outstanding Advances	0.00%	2.70%
Purchases of FHLB Stock	$ 15,600
Redemptions of FHLB stock	13,400
Federal Home Loan Bank of San Francisco [Member]
Schedule of Available-for-sale Securities [Line Items]
Increase (Decrease) in Marketable Securities, Restricted	2,200
Available-for-sale Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Proceeds from sales of securities available-for-sale	$ 384,000	$ 208,400	138,100
Capitalsource, Inc. [Member]
Schedule of Available-for-sale Securities [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Marketable Securities					$ 382,797
Square 1 Financial, Inc. [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Realized Gains		0
Square 1 Financial, Inc. [Member] | Available-for-sale Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Proceeds from sales of securities available-for-sale		$ 823,800
Square 1 Financial, Inc. [Member] | Square 1 Financial, Inc. [Member] | Available-for-sale Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Marketable Securities				$ 2,200,000
Capitalsource, Inc. [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Realized Gains			0
Capitalsource, Inc. [Member] | Available-for-sale Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Proceeds from sales of securities available-for-sale			$ 322,700