Acquisitions - Security California Bancorp table (Details) - USD ($) $ in Thousands	Jan. 31, 2016	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Business Acquisition [Line Items]
Goodwill		$ 102,085	$ 50,832	$ 51,010
Security California Bancorp
Business Acquisition [Line Items]
Cash and cash equivalents	$ 40,947
Interest bearing deposits with financial institutions	1,972
Investment securities	190,254
Loans, gross		$ 456,158
Allowance for loan losses	0
Fixed assets	4,356
Core deposit intangible	4,319
Deferred income taxes	7,069
Other assets	9,281
Total assets acquired	714,356
Deposits	636,591
Other Liabilities	8,843
Total liabilities assumed	645,434
Excess of assets acquired over liabilities assumed	68,922
Consideration paid	120,174
Goodwill	51,252
SCAF Book Value | Security California Bancorp
Business Acquisition [Line Items]
Cash and cash equivalents	40,947
Interest bearing deposits with financial institutions	1,972
Investment securities	191,881
Loans, gross	467,197
Allowance for loan losses	(7,399)
Fixed assets	5,335
Core deposit intangible	493
Deferred income taxes	5,618
Other assets	10,589
Total assets acquired	716,633
Deposits	636,450
Other Liabilities	9,063
Total liabilities assumed	645,513
Excess of assets acquired over liabilities assumed	71,120
Fair Value Adjustments | Security California Bancorp
Business Acquisition [Line Items]
Cash and cash equivalents	0
Interest bearing deposits with financial institutions	0
Investment securities	(1,627)
Loans, gross	(11,039)
Allowance for loan losses	7,399
Fixed assets	(979)
Core deposit intangible	3,826
Deferred income taxes	1,451
Other assets	(1,308)
Total assets acquired	(2,277)
Deposits	141
Other Liabilities	(220)
Total liabilities assumed	(79)
Excess of assets acquired over liabilities assumed	$ (2,198)