Investments (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Oct. 06, 2015	Apr. 07, 2014	May. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Available For Sale Securities Pledged As Collateral Amortized Cost	$ 421,600,000
Proceeds from sales	1,035,926,000	$ 465,608,000	$ 22,415,000
Payments to Acquire Investments	992,700,000	236,700,000	550,200,000
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Reclassification Adjustments, Net of Tax	3,621,000	32,601,000	$ (30,946,000)
Federal Home Loan Bank stock, at cost	19,710,000	40,609,000
Redemptions of FHLB stock	(31,300,000)
Purchases of FHLB Stock	7,600,000
Government agency and government-sponsored enterprise pass through securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Proceeds from sales	30,800,000
Texas Municipal Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Realized Gains	744,000
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Proceeds from sales	67,500,000
Available-for-sale Securities, Gross Realized Losses	232,000
Government agency and government-sponsored enterprise pass through securities
Schedule of Available-for-sale Securities [Line Items]
Proceeds from sales	110,100,000	460,800,000
Available-for-sale Securities, Gross Realized Gains	3,200,000	4,800,000
Square 1 Financial, Inc. [Member]
Schedule of Available-for-sale Securities [Line Items]
Proceeds from sales	823,800,000
Available-for-sale Securities, Gross Realized Gains	0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Marketable Securities				$ 2,193,538,000
Federal Home Loan Bank stock, at cost				$ 2,800,000
Capitalsource, Inc. [Member]
Schedule of Available-for-sale Securities [Line Items]
Proceeds from sales		322,700,000
Available-for-sale Securities, Gross Realized Gains		$ 0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Marketable Securities					$ 382,797,000
First California Financial Group, Inc. [Member]
Schedule of Available-for-sale Securities [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Marketable Securities						$ 4,444,000
Federal Home Loan Bank of San Francisco [Member]
Schedule of Available-for-sale Securities [Line Items]
Increase (Decrease) in Marketable Securities, Restricted	$ (20,900,000)