Acquisitions - Security California Bancorp - Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Jan. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Jan. 26, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill recognized		$ 102,490	$ 50,832		$ 22,950
Security California Bancorp
Business Acquisition [Line Items]
Cash and cash equivalents	$ 40,947
Investment securities	190,254
Loans, gross	456,158
Allowance for loan losses	0
Fixed assets	4,190
Core deposit intangible	4,319
Deferred tax assets	6,748
Other assets	9,362
Total assets acquired	713,950
Deposits	636,591
Borrowings	0
Deferred tax liability	0
Other liabilities	8,843
Total liabilities assumed	645,434
Excess of assets acquired over liabilities assumed	68,516
Consideration paid	120,174
Goodwill recognized	51,658			$ 51,700
Security California Bancorp | Bank Time Deposits
Business Acquisition [Line Items]
Cash and cash equivalents	1,972
Security California Bancorp | As initially reported
Business Acquisition [Line Items]
Cash and cash equivalents	40,947
Investment securities	191,881
Loans, gross	467,197
Allowance for loan losses	(7,399)
Fixed assets	5,335
Core deposit intangible	493
Deferred tax assets	5,618
Other assets	10,589
Total assets acquired	716,633
Deposits	636,450
Borrowings	0
Deferred tax liability	0
Other liabilities	9,063
Total liabilities assumed	645,513
Excess of assets acquired over liabilities assumed	71,120
Security California Bancorp | As initially reported | Bank Time Deposits
Business Acquisition [Line Items]
Cash and cash equivalents	1,972
Security California Bancorp | Fair Value Adjustments
Business Acquisition [Line Items]
Cash and cash equivalents	0
Investment securities	(1,627)
Loans, gross	(11,039)
Allowance for loan losses	7,399
Fixed assets	(1,145)
Core deposit intangible	3,826
Deferred tax assets	1,130
Other assets	(1,227)
Total assets acquired	(2,683)
Deposits	141
Borrowings	0
Deferred tax liability	0
Other liabilities	(220)
Total liabilities assumed	(79)
Excess of assets acquired over liabilities assumed	(2,604)
Security California Bancorp | Fair Value Adjustments | Bank Time Deposits
Business Acquisition [Line Items]
Cash and cash equivalents	$ 0